Detection device and electronic auscultation device

Abstract

This detection device for detecting vibration of a subject includes: a diaphragm including a reflection surface that moves according to the vibration of the subject; a first light emitting unit that emits first light toward the reflection surface; a first light receiving unit that receives the first light reflected by the reflection surface and outputs a signal corresponding to the first light; a second light emitting unit that emits second light toward the reflection surface; and a second light receiving unit that receives the second light reflected by the reflection surface and outputs a signal corresponding to the second light. An incident angle of the first light with respect to the reflection surface is larger than an incident angle of the second light with respect to the reflection surface.

Description

Detection Device and Electronic Stethoscope

[0001] The present invention relates to a detection device for detecting vibrations of a subject and an electronic stethoscope for performing auscultation.

[0002] In recent years, electronic stethoscopes equipped with sensors for converting biological vibrations into electrical signals, capable of reproducing biological sounds via playback devices such as earphones or outputting them as electronic data representing biological sounds to external devices, have begun to spread. Japanese Unexamined Patent Application Publication No. 2022-119446 proposes an electronic stethoscope that collects biological sounds using a capacitive microphone. Japanese Unexamined Patent Application Publication No. 2017-47095 proposes an electronic stethoscope that acquires biological sounds using a vibration sensor.

[0003] Conventionally, there has been no progress in the study of electronic stethoscopes equipped with optical detection devices that convert vibrations of a subject into electrical signals using light. Also, a configuration has been required that can accurately detect multiple types of vibrations with different amplitudes using a single detection device.

[0004] Therefore, an object of the present invention is to provide a detection device and an electronic stethoscope capable of accurately detecting multiple types of vibrations.

[0005] One aspect of the present invention is a detection device for detecting vibrations of a subject, comprising: a diaphragm including a reflecting surface that moves in response to vibrations of the subject; a first light-emitting portion that emits first light toward the reflecting surface; a first light-receiving portion that receives the first light reflected by the reflecting surface and outputs a signal corresponding to the first light; a second light-emitting portion that emits second light toward the reflecting surface; and a second light-receiving portion that receives the second light reflected by the reflecting surface and outputs a signal corresponding to the second light, wherein an incident angle of the first light with respect to the reflecting surface is larger than an incident angle of the second light with respect to the reflecting surface.

[0006] Another aspect of the present invention is a detection device for detecting vibrations of a subject, comprising: a diaphragm including a reflective surface that moves in response to the vibrations of the subject; a first light-emitting unit that emits a first light toward the reflective surface; a first light-receiving unit that receives the first light reflected by the reflective surface and outputs a signal corresponding to the first light; a second light-emitting unit that emits a second light toward the reflective surface; a second light-receiving unit that receives the second light reflected by the reflective surface and outputs a signal corresponding to the second light; a first aperture that narrows the optical path of the first light so that the amount of the first light reaching the first light-receiving unit changes in response to the displacement of the reflective surface; and a second aperture that narrows the optical path of the second light so that the amount of the second light reaching the second light-receiving unit changes in response to the displacement of the reflective surface, wherein the aperture area of ​​the first aperture is smaller than the aperture area of ​​the second aperture.

[0007] The present invention aims to provide a detection device and an electronic auscultation device capable of accurately detecting multiple types of vibrations.

[0008] Figure 1 shows the external appearance of an electronic stethoscope (a, b).

[0009] Figure 2 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the first embodiment.

[0010] Figure 3 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the first embodiment.

[0011] Figure 4 shows cross-sectional views (a, b) of the chestpiece representing the displacement of the vibrating membrane in the first embodiment.

[0012] Figure 5 is a schematic diagram (a, b) showing an example of the movement of reflected light in the first embodiment.

[0013] Figure 6 shows the relationship between the diaphragm displacement and the displacement signal in the first embodiment.

[0014] Figure 7 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the second embodiment.

[0015] Figure 8 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the second embodiment.

[0016] Figure 9 shows cross-sectional views (a, b) of the chestpiece representing the displacement of the vibrating membrane in the second embodiment.

[0017] Figure 10 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the second embodiment.

[0018] Figure 11 shows the relationship between the diaphragm displacement and the displacement signal in the second embodiment.

[0019] Figure 12 shows the relationship between the diaphragm displacement and the displacement signal in the second embodiment.

[0020] Figure 13 is a schematic diagram showing the configuration of a chestpiece according to the first embodiment.

[0021] Figure 14 is a schematic diagram (a, b) illustrating the principle of an optical vibration detection mechanism.

[0022] Figure 15 is a schematic diagram (a, b) illustrating the principle of an optical vibration detection mechanism.

[0023] Figure 16 is a schematic diagram illustrating the principle of an optical vibration detection mechanism.

[0024] Figure 17 is a graph illustrating the principle of an optical vibration detection mechanism.

[0025] Figure 18 is a block diagram showing the hardware configuration of an electronic stethoscope according to the first embodiment.

[0026] Figure 19 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the third embodiment.

[0027] Figure 20 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the third embodiment.

[0028] Figure 21 is a schematic diagram (a, b) showing an example of the movement of reflected light in the third embodiment.

[0029] Figure 22 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the fourth embodiment.

[0030] Figure 23 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the fourth embodiment.

[0031] Figure 24 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the fourth embodiment.

[0032] Figure 25 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the fourth embodiment.

[0033] Figure 26 shows the relationship between the diaphragm displacement and the displacement signal in the fourth embodiment.

[0034] Figure 27 shows the relationship between the diaphragm displacement and the signal ratio in the fourth embodiment.

[0035] Figure 28 is a block diagram showing the hardware configuration of an electronic stethoscope according to the third embodiment.

[0036] Figure 29 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the fifth embodiment.

[0037] Figure 30 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the fifth embodiment.

[0038] Figure 31 is a schematic diagram showing an example of the movement of reflected light in the fifth embodiment.

[0039] Figure 32 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the sixth embodiment.

[0040] Figure 33 shows a cross-sectional view (a) and an internal view (b) of the chestpiece in the sixth embodiment.

[0041] Figure 34 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the sixth embodiment.

[0042] Figure 35 is a cross-sectional view (a, b) of the chestpiece showing the displacement of the vibrating membrane in the sixth embodiment.

[0043] FIG. 36 is a diagram showing the relationship between the displacement amount and the displacement signal of the diaphragm in the sixth embodiment.

[0044] FIG. 37 is a block diagram showing the hardware configuration of the electronic stethoscope according to the fifth embodiment.

[0045] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, all of these plurality of features are not necessarily essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted. 《First Embodiment》

[0046] The electronic stethoscope 100 according to the first embodiment will be described with reference to FIGS. 1(a) to 6. In each of the following drawings, a coordinate system CS, which is a three-dimensional orthogonal coordinate system having an x-axis, a y-axis, and a z-axis, may be attached to explain the directions. In those explanations, the positive direction of the z-axis may be represented as the upper side, and the negative direction of the z-axis may be represented as the lower side.

[0047] FIG. 1(a) shows the appearance of the electronic stethoscope 100 when viewed from a certain direction. FIG. 1(b) shows the appearance of the electronic stethoscope 100 when viewed from another direction. The electronic stethoscope 100 is a diagnostic instrument for listening to internal sounds of a living body such as a human or an animal. The electronic stethoscope 100 is used, for example, to listen to heart sounds (heartbeat sounds) and breathing sounds.

[0048] As shown in FIGS. 1(a) and 1(b), the electronic stethoscope 100 includes a chest piece 110 and a grip portion 120. The chest piece 110 is a unit that, during diagnosis using the electronic stethoscope 100, contacts the surface of a living body, which is an example of a subject (measurement target), measures minute vibrations (displacements) on the surface of the living body, and captures body sounds. The chest piece 110 detects minute displacements on the surface of the closely adhered living body via a diaphragm 206 described later. Therefore, the chest piece 110 can also be referred to as a displacement detection device or a diaphragm displacement detection device. Further, the chest piece 110 can also be referred to as a detection device for detecting vibrations on the living body surface or a living body vibration detection device.

[0049] The grip portion 120 is gripped when a user (e.g., a doctor, nurse, or healthcare worker) of the electronic stethoscope 100 brings the diaphragm 206 into close contact with the living body surface. Hereinafter, the user of the electronic stethoscope 100 will simply be referred to as the user. As shown in FIGS. 1(a) and 1(b), the grip portion 120 has a rod shape, and the chest piece 110 is attached to one end (the negative direction of the x-axis) side. The grip portion 120 is called a handle, a grip, a knob, etc.

[0050] The grip portion 120 includes a housing 121, a battery and a circuit board housed inside the housing 121. The battery stores the operating power of the electronic stethoscope 100. The circuit board has circuit elements for controlling the operation of the electronic stethoscope 100. The grip portion 120 has a display portion 122, an operation portion 123, a power switch 124, and a connector 125, which are respectively arranged on the outer surface of the housing 121.

[0051] The display unit 122 displays the status of the electronic stethoscope 100. For example, the display unit 122 includes a plurality of indicators (four indicators in the example of Figure 1(a)). Each indicator is composed of a light-emitting diode (LED). The plurality of indicators include an indicator that shows whether the power of the electronic stethoscope 100 is on or off. The plurality of indicators also include an indicator that shows the current operating mode of the electronic stethoscope 100. The plurality of indicators also include an indicator that shows whether the electronic stethoscope 100 is wirelessly connected to an external device. The plurality of indicators also include an indicator that shows whether the chestpiece 110 is pressed against a biological surface. As shown in Figure 1(a), the display unit 122 is located near the chestpiece 110 on one end in the x-axis direction of the outer surface of the housing 121, on the side opposite to the chestpiece 110. In this embodiment, "near the chestpiece 110" means closer to the chestpiece 110 than the center of the gripping unit 120. The display unit 122 does not need to include all of the indicators mentioned above, and the status of the electronic stethoscope 100 may be displayed by a liquid crystal panel or an electrostatic panel instead of, or in addition to, multiple indicators.

[0052] The control unit 123 receives input from the user. In this embodiment, the control unit 123 includes a plurality of physical buttons (three buttons in the example of Figure 1(a)) for receiving settings for the electronic stethoscope 100. Specifically, the control unit 123 includes volume adjustment buttons (volume up button 123a and volume down button 123b) for adjusting the volume of the output sound. When the volume adjustment buttons are pressed, the electronic stethoscope 100 adjusts the gain of the signal output from the light-receiving element 204 and adjusts the volume of the sound output through the earphones. The control unit 123 includes a mode switching button 123c for switching the operating mode of the electronic stethoscope 100. When the mode switching button 123c is pressed, the operating mode described later is switched. That is, the mode switching button 123c receives instructions from the user regarding the mode transition of the electronic stethoscope 100. Based on the instructions from the user using the mode switching button 123c, the electronic stethoscope 100 selects one of a plurality of operating modes and operates in that operating mode. The operation unit 123 may include a touch panel instead of multiple physical buttons. The display unit 122 and the operation unit 123 may be integrated as a touchscreen. The electronic stethoscope 100 may automatically select an operating mode in response to a signal representing vibrations of the biological surface, instead of, or in addition to, instructions from the user using the mode switching button 123c.

[0053] The power switch 124 is a switch that turns the power of the electronic stethoscope 100 on and off. The connector 125 is a connector for receiving a cable or connector of an external device. Power is supplied from the external device to the battery included in the gripping part 120 through the connector 125.

[0054] In this embodiment, the electronic stethoscope 100 includes both a chestpiece 110 and a gripping portion 120. However, it may also be configured to include only the chestpiece 110 and not the gripping portion 120. [Cross-sectional configuration of the chestpiece]

[0055] The chestpiece 110 according to the first embodiment will be described with reference to Figures 2(a) and 2(b), Figures 3(a) and 3(b), and Figure 13. Figure 2(a) is a cross-sectional view of the chestpiece 110 in the section shown by line A-A in Figure 2(b). Figure 2(b) is a plan view (viewed in the negative z-axis direction) showing the internal layout of the chestpiece 110. Figure 3(a) is a cross-sectional view of the chestpiece 110 in the section shown by line B-B in Figure 3(b). Figure 3(b) is a plan view showing the internal layout of the chestpiece 110. In Figures 2(b) and 3(b), the components other than the housing 208 of the chestpiece 110 are shown by viewing the housing 208 through the housing 208. The upper part of Figure 13 is a schematic diagram corresponding to the cross-section of the chestpiece 110 shown in Figure 2(a), and the lower part of Figure 13 is a schematic diagram showing the positional relationship of the elements when viewed in the z-axis direction.

[0056] As shown in Figures 2(a) to 3(b) and Figure 13, the chestpiece 110 includes a holding member 201, light-emitting circuit boards (203a, 203b), and light-receiving circuit boards (205a, 205b). Light-emitting elements (202a, 202b) are mounted on the light-emitting circuit boards, and light-receiving elements (204a, 204b) are mounted on the light-receiving circuit boards. The chestpiece 110 also includes a diaphragm 206 including a light-reflecting portion 207 (reflecting surface) and a housing 208.

[0057] The chestpiece 110 according to this embodiment has a plurality of light-emitting units and a plurality of light-receiving units. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit. In other words, the chestpiece 110 has a first light-emitting circuit board 203a as a first light-emitting unit, a second light-emitting circuit board 203b as a second light-emitting unit, a first light-receiving circuit board 205a as a first light-receiving unit, and a second light-receiving circuit board 205b as a second light-receiving unit.

[0058] Hereinafter, a set consisting of one light-emitting unit (light-emitting circuit board) and a corresponding light-receiving unit (light-receiving circuit board) may be referred to as an optical detection pair. In this embodiment, an example in which two sets of optical detection pairs are arranged in the chest piece 110 is described, but three or more sets of optical detection pairs may be arranged in the chest piece 110.

[0059] The housing 208 houses the holding member 201, the light-emitting circuit boards (203a, 203b), and the light-receiving circuit boards (205a, 205b) inside. Since the holding member 201 has aperture sections (209a, 209b, 210a, 210b), the housing 208 can house the aperture sections inside. Note that the components of the chestpiece 110 described here are just examples, and in addition to the components described above, the chestpiece 110 may also have, for example, a circuit board on which circuit elements for controlling the operation of the chestpiece 110 are mounted.

[0060] Each of the first light-emitting element 202a and the second light-emitting element 202b is a light source that emits light, and may be, for example, a light-emitting diode (LED). Power is supplied to the first light-emitting element 202a and the second light-emitting element 202b from an external power source (the battery of the gripping part 120) of the chestpiece 110.

[0061] The first light-emitting element 202a is mounted on the first light-emitting circuit board 203a, and the second light-emitting element 202b is mounted on the second light-emitting circuit board 203b. In addition to the first light-emitting element 202a, the first light-emitting circuit board 203a is mounted with peripheral circuits for defining the amount of light emitted by the first light-emitting element 202a and power terminals for receiving power from an external power source to the chestpiece 110. In addition to the second light-emitting element 202b, the second light-emitting circuit board 203b is mounted with peripheral circuits for defining the amount of light emitted by the second light-emitting element 202b and power terminals for receiving power from an external power source to the chestpiece 110. The first light-emitting circuit board 203a and the second light-emitting circuit board 203b may be printed circuit boards such as flexible circuit boards, or they may be paper phenolic substrates or glass epoxy substrates.

[0062] The first light-emitting circuit board 203a, which includes the first light-emitting element 202a, functions as a first light-emitting unit. The second light-emitting circuit board 203b, which includes the second light-emitting element 202b, functions as a second light-emitting unit.

[0063] In this embodiment, there is one first light-emitting element 202a arranged on the first light-emitting circuit board 203a, and one second light-emitting element 202b arranged on the second light-emitting circuit board 203b. However, multiple light-emitting elements (multiple first light-emitting elements 202a) may be arranged on the first light-emitting circuit board 203a, and multiple light-emitting elements (multiple second light-emitting elements 202b) may be arranged on the second light-emitting circuit board 203b. In other words, the "first light-emitting section" may include multiple light-emitting elements arranged on a single insulating substrate. Also, the "second light-emitting section" may include multiple light-emitting elements arranged on a single insulating substrate different from the insulating substrate of the first light-emitting section.

[0064] The first light-receiving element 204a and the second light-receiving element 204b generate an electrical signal based on the amount of light they receive, using power supplied from a battery housed inside the gripping part 120. The power supplied to the first light-receiving element 204a and the second light-receiving element 204b is supplied from the battery in the gripping part 120. The first light-receiving element 204a and the second light-receiving element 204b may be, for example, phototransistors or complementary metal-oxide-semiconductor (CMOS) sensors.

[0065] The first light-receiving element 204a is mounted on the first light-receiving circuit board 205a, and the second light-receiving element 204b is mounted on the second light-receiving circuit board 205b. In addition to the first light-receiving element 204a, the first light-receiving circuit board 205a is mounted with peripheral circuits for reading signals from the first light-receiving element 204a. In addition to the second light-receiving element 204b, the second light-receiving circuit board 205b is mounted with peripheral circuits for reading signals from the second light-receiving element 204b. Furthermore, the first light-receiving circuit board 205a and the second light-receiving circuit board 205b are each mounted with terminals for outputting signals to the outside of the chestpiece 110 and power supply terminals for receiving power from an external power supply to the chestpiece 110. The first light-receiving circuit board 205a and the second light-receiving circuit board 205b may each be a printed circuit board such as a flexible circuit board, or a paper phenolic substrate or a glass epoxy substrate.

[0066] The first light-receiving circuit board 205a, which includes the first light-receiving element 204a, functions as a first light-receiving unit. The second light-receiving circuit board 205b, which includes the second light-receiving element 204b, functions as a second light-receiving unit.

[0067] In this embodiment, there is one first light-receiving element 204a on the first light-receiving circuit board 205a and one second light-receiving element 204b on the second light-receiving circuit board 205b. However, multiple first light-receiving elements 204a may be arranged on the first light-receiving circuit board 205a, and multiple second light-receiving elements 204b may be arranged on the second light-receiving circuit board 205b. In other words, the "first light-receiving unit" may include multiple light-receiving elements arranged on a single insulating substrate. The "second light-receiving unit" may also include multiple light-receiving elements arranged on a separate insulating substrate from the insulating substrate of the first light-receiving unit. Furthermore, the multiple light-receiving elements constituting the first light-receiving unit may constitute a line sensor (1 × n (n≧2) light-receiving elements) or an area sensor (m × n (m≧2, n≧2) light-receiving elements). The multiple light-receiving elements constituting the second light-receiving unit may constitute a line sensor (1 × n (n ≥ 2) light-receiving elements) or an area sensor (m × n (m ≥ 2, n ≥ 2) light-receiving elements).

[0068] As shown in Figures 2(a) and 3(a), the angle with respect to the diaphragm 206 is different for the optical path from the first light-emitting element 202a to the light-reflecting element 207 and for the optical path from the second light-emitting element 202b to the light-reflecting element 207. The angle of incidence of the light emitted by the first light-emitting element 202a (first light) to the light-reflecting element 207 is greater than the angle of incidence of the light emitted by the second light-emitting element 202b (second light) to the light-reflecting element 207. The advantages of this configuration will be described later.

[0069] The pair of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a (first optical detection pair) and the pair of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b (second optical detection pair) are in a positional relationship where they are rotated relative to each other around the center 206e of the diaphragm 206. In other words, when one optical detection pair is rotated around an axis perpendicular to the diaphragm 206, it overlaps with the other optical detection pair. More specifically, in this embodiment, when the first optical detection pair is rotated 90° around an axis extending in the z-axis direction through the center 206e of the diaphragm 206, it overlaps with the second optical detection pair. In other words, when viewed in the z-axis direction, the optical path of light from the first light-emitting unit to the first light-receiving unit and the optical path of light from the second light-emitting unit to the second light-receiving unit intersect at a predetermined angle (90° in this embodiment).

[0070] In this embodiment, multiple optical detection pairs, each including a light-emitting unit and a light-receiving unit, are arranged, and the optical paths of the first optical detection pair and the second optical detection pair intersect when viewed in the z-axis direction. This makes it possible to avoid a decrease in detection accuracy due to light interference between optical detection pairs (light emitted from the light-emitting unit of one optical detection pair entering the light-receiving unit of the other optical detection pair).

[0071] Furthermore, for example, when viewed in the z-axis direction, the optical paths of the first optical detection pair and the second optical detection pair intersect at the center 206e of the diaphragm 206. In other words, within the light reflecting portion 207, the area where light from the first light-emitting element 202a is irradiated when the diaphragm 206 is not pressed by a living organism (first effective range) is defined as region 207a (Figure 13). Also, the area where light from the second light-emitting element 202b is irradiated when the diaphragm 206 is not pressed by a living organism (second effective range) is defined as region 207b. In this case, both region 207a (first effective range) and region 207b (second effective range) overlap with the center 206e of the diaphragm 206 when viewed in the z-axis direction. As a result, for each of the first and second optical detection pairs, the displacement of the living organism surface 320 can be detected using the central part where the displacement of the diaphragm 206 is greatest, thereby improving the accuracy of detecting living organism sounds.

[0072] The holding member 201 holds the first light-emitting circuit board 203a, the second light-emitting circuit board 203b, the first light-receiving circuit board 205a, and the second light-receiving circuit board 205b. Each light-emitting circuit board and each light-receiving circuit board is fixed to the holding member 201. These boards may be fixed to the holding member 201 using adhesive or fasteners such as screws.

[0073] The diaphragm 206 has a contact surface 206a (outer surface) that contacts a biological surface, which is an example of a subject, and an inner surface 206b that is the surface opposite to the contact surface 206a. The diaphragm 206 is configured to elastically deform when pressed by a subject that is in contact with the contact surface 206a. The inner surface 206b of the diaphragm 206 is provided with a light-reflecting portion 207, which will be described later. The diaphragm 206 may be a laminate of glass epoxy resin obtained by impregnating glass fibers with epoxy resin and then heat-curing it.

[0074] The diaphragm 206 may have a multilayer structure. In that case, the surface of the outermost layer of the multilayer diaphragm 206 that comes into contact with the subject is defined as the contact surface 206a, and the surface of the innermost layer on which the light-reflecting portion 207 is provided is defined as the inner surface 206b. The diaphragm 206 may be composed of multiple layers or members, as long as they vibrate integrally with the subject it comes into contact with. Furthermore, in the case where a separate cover is attached to the contact surface 206a of the diaphragm 206 in this embodiment, if the cover and the contact surface 206a vibrate integrally with the subject, then the cover and the diaphragm 206 can be said to be a form of "diaphragm". In addition, when the electronic stethoscope 100 is in use, the contact surface 206a of the diaphragm 206 is exposed to the outside, and when not in use, the contact surface 206a may be covered by a protective cover or case to suppress damage or deterioration of the contact surface 206a.

[0075] The diaphragm 206 is held by the retaining member 201. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 is positioned to contact a biological surface, which is an example of a subject. The contact surface 206a of the diaphragm 206 is exposed to the outside of the housing 208. Together with the housing 208, the diaphragm 206 constitutes part of the exterior of the chestpiece 110 (the exterior of the electronic stethoscope 100).

[0076] The outer circumference of the diaphragm 206 has a ring-shaped fixing portion 206c (rim) for fixing the diaphragm 206 to the retaining member 201 or the housing 208. In this embodiment, the fixing portion 206c on the outer circumference is integrally formed with the inner circumference portion of the fixing portion 206c. In this embodiment, the contact surface 206a and inner surface 206b of the diaphragm 206 refer to the portion that does not include the fixing portion 206c. Inside the fixing portion 206c of the diaphragm 206, the diaphragm 206 is not fixed to the retaining member 201. Therefore, the diaphragm 206 can vibrate in the z-axis direction with the fixing portion 206c as a node. Specifically, when the chestpiece 110 is used, the diaphragm 206 vibrates with the fixing portion 206c as a node in accordance with the displacement of the biological surface. In this vibration, the center 206e of the diaphragm 206 becomes an antinode. The diaphragm 206 functions as a vibrating part that vibrates together with the subject.

[0077] The light-reflecting portion 207 is a reflective surface that reflects light emitted from the first light-emitting element 202a or the second light-emitting element 202b. In this embodiment, the light-reflecting portion 207 is bonded to the inner surface 206b of the diaphragm 206 and moves integrally with the diaphragm 206 in the z-axis direction in conjunction with the vibration of the diaphragm 206, which is in close contact with the biological surface. The light-reflecting portion 207 has a circular outer edge in the plan view. The light-reflecting portion 207 has a diameter of, for example, 15 mm to 20 mm. The light-reflecting portion 207 is positioned to cover a region 206d that includes the center 206e of the circle of the diaphragm 206. Since the displacement of the diaphragm 206 is greatest at the center 206e, the displacement of the diaphragm 206 can be detected with high sensitivity by reflecting light from the first light-emitting element 202a or the second light-emitting element 202b in the region including the center 206e. The light-reflecting portion 207 may be placed in a region of the diaphragm 206 that does not include the central part 206e.

[0078] The light-reflecting portion 207 is made of, for example, an aluminum vapor-deposited film. The light-reflecting portion 207 is a sheet-like member attached to the inner surface 206b (the surface opposite to the contact surface 206a) of the base material (sheet material) that constitutes the diaphragm 206.

[0079] In this embodiment, the light-reflecting portion 207 is part of the diaphragm 206. That is, the sheet-like light-reflecting portion 207 attached to the inner surface 206b of the substrate of the diaphragm 206, together with the substrate of the diaphragm 206, constitutes the diaphragm 206. However, it is not limited to this configuration, and at least a portion of the inner surface 206b of the substrate of the diaphragm 206 may also serve as the light-reflecting portion. Alternatively, a coating layer may be applied to the diaphragm 206, and the coating layer may be configured as the light-reflecting portion. For example, the entire inner surface 206b of the diaphragm 206 may have a high reflectivity such that it can reflect light to an extent detectable by the first light-receiving element 204a and the second light-receiving element 204b. Alternatively, only the region of the inner surface 206b of the diaphragm 206 that reaches the light emitted from the first light-emitting element 202a or the second light-emitting element 202b may have such a high reflectivity.

[0080] The first light-emitting element 202a and the second light-emitting element 202b emit light toward the inner surface 206b of the diaphragm 206. The upper surface of the light-reflecting part 207 reflects the light emitted from the first light-emitting element 202a and the second light-emitting element 202b. That is, the upper surface of the light-reflecting part 207 in particular functions as a light-reflecting surface. In the following description, the reflection of light by the upper surface (light-reflecting surface) of the light-reflecting part 207 will simply be referred to as "light being reflected by the light-reflecting part 207". The light-reflecting part 207 specularly reflects (in other words, mirror-reflects) the light emitted from the first light-emitting element 202a and the second light-emitting element 202b.

[0081] In the following description, the light directed from the first light-emitting element 202a and the second light-emitting element 202b toward the light-reflecting element 207 will be referred to as the first incident light 211a and the second incident light 211b, respectively. The light after the first incident light 211a and the second incident light 211b have been reflected will be referred to as the first reflected light 212a and the second reflected light 212b, respectively.

[0082] The first light-emitting element 202a and the second light-emitting element 202b are arranged to emit light toward regions 207a and 207b (Figure 13) of the light-reflecting portion 207 that cover the central part 206e of the diaphragm 206 when the diaphragm 206 is not in contact with the biological surface. When the diaphragm 206 is not in contact with the biological surface, the diaphragm 206 is flat. The first light-emitting element 202a and the second light-emitting element 202b emit light toward specific regions of the light-reflecting portion 207 (for example, regions 207a and 207b).

[0083] In this embodiment, a light source (LED) that emits diffuse light is used as the first light-emitting element 202a and the second light-emitting element 202b. Therefore, the chestpiece 110 has a first aperture portion 209a and a second aperture portion 209b that narrow the light emitted from the first light-emitting element 202a and the second light-emitting element 202b. The first aperture portion 209a ensures that only a portion of the first incident light 211a emitted from the first light-emitting element 202a enters the light-reflecting portion 207. Similarly, the second aperture portion 209b ensures that only a portion of the second incident light 211b emitted from the second light-emitting element 202b enters the light-reflecting portion 207.

[0084] In the examples of Figures 2(a) and 3(a) and 3(b), the portion of the holding member 201 through which the first incident light 211a passes corresponds to the first aperture portion 209a. The portion of the holding member 201 through which the second incident light 211b passes corresponds to the second aperture portion 209b.

[0085] In this embodiment, a component that emits diffused light was described as an example of a light-emitting element. However, instead, a laser diode or the like that emits linear light may be used as a light-emitting element, and the linear light may be directed toward region 207a. If the light-emitting element is a component that emits linear light, the aperture portion may be omitted.

[0086] The first light-receiving element 204a and the second light-receiving element 204b are arranged to receive the first reflected light 212a and the second reflected light 212b, respectively. Specifically, the first light-receiving element 204a is positioned so that the amount of first reflected light 212a received changes due to the vibration of the diaphragm 206 in the z-axis direction. The second light-receiving element 204b is positioned so that the amount of second reflected light 212b received changes due to the vibration of the diaphragm 206 in the z-axis direction.

[0087] The first light-receiving element 204a and the second light-receiving element 204b are positioned so that more light is incident on the diaphragm 206 when it is not in contact with the biological surface (i.e., when the diaphragm 206 is flat) compared to when the diaphragm 206 is vibrating. In other words, the first light-receiving element 204a and the second light-receiving element 204b output electrical signals corresponding to the amount of first reflected light 212a and second reflected light 212b they receive, and the amount of displacement of the diaphragm 206 can be determined based on these electrical signals. This principle will be described later.

[0088] Furthermore, the chestpiece 110 has a third aperture section 210a and a fourth aperture section 210b that narrow the light specularly reflected by the light reflecting section 207. The third aperture section 210a suppresses diffusely reflected light from entering the first light-receiving element 204a, allowing only specularly reflected light from the light reflecting section 207 to reach the first light-receiving element 204a. The fourth aperture section 210b suppresses diffusely reflected light from entering the second light-receiving element 204b, allowing only specularly reflected light from the light reflecting section 207 to reach the second light-receiving element 204b. In addition, the third aperture section 210a and the fourth aperture section 210b further narrow the specularly reflected light from the light reflecting section 207, allowing only a portion of the specularly reflected light to reach the first light-receiving element 204a and the second light-receiving element 204b.

[0089] The third aperture portion 210a functions as a first aperture that narrows the optical path from the light-reflecting portion 207 to the first light-receiving element 204a so that the area of ​​the portion of the light-receiving surface of the first light-receiving element 204a that receives light changes according to the amount of displacement of the light-reflecting portion 207. The fourth aperture portion 210b functions as a second aperture that narrows the optical path from the light-reflecting portion 207 to the second light-receiving element 204b so that the area of ​​the portion of the light-receiving surface of the second light-receiving element 204b that receives light changes according to the amount of displacement of the light-reflecting portion 207.

[0090] In the examples of Figures 2(a) and 3(a) and 3(b), the portion of the holding member 201 through which the first reflected light 212a passes corresponds to the third diaphragm portion 210a (first opening). The portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth diaphragm portion 210b (second opening).

[0091] In this embodiment, the portion of the holding member 201 in which an opening is formed was described as an example of a diaphragm (209a, 209b, 210a, 210b), but it may be a diaphragm on one side instead of an opening. In that case, for example, the diaphragm (opening) is formed by a light-shielding wall for narrowing one side (upper or lower) of the light emitted from the light-emitting element, and an opening whose opening area is limited by the light-shielding wall.

[0092] A housing 208 is attached to the outer upper surface of the retaining member 201. The housing 208 covers the first light-emitting circuit board 203a and the second light-emitting circuit board 203b, as well as the first light-receiving circuit board 205a and the second light-receiving circuit board 205b, and also suppresses ambient noise from entering the housing 208.

[0093] The outer edge of the diaphragm 206, the outer edge of the retaining member 201, and the outer edge of the housing 208 substantially coincide with each other in a plan view with respect to the contact surface 206a of the diaphragm 206. In this embodiment, the housing 208 is made of metal, and the ground of the circuit boards (e.g., light-emitting circuit board and light-receiving circuit board) in the chestpiece 110 is electrically connected to the housing 208. This stabilizes the ground potential.

[0094] The diaphragm 206 is fixed to the retaining member 201, forming an internal space 213 surrounded by the diaphragm 206 and the retaining member 201. It is preferable that the internal space 213 be sealed in order to prevent the light receiving element from receiving light other than that emitted by the light-emitting element. Furthermore, it is preferable that the diaphragm 206 and the retaining member 201 have light-shielding properties in order to prevent the light receiving element from receiving light other than that emitted by the light-emitting element.

[0095] In the examples shown in Figures 2(a) and 3(a), the fixing portion 206c of the diaphragm 206 is fixed to the holding member 201. Alternatively, the fixing portion 206c of the diaphragm 206 may be fixed to the housing 208. [Example of operation of the electronic stethoscope according to the first embodiment]

[0096] Referring to Figures 4(a) and 4(b), a basic example of the operation of the chestpiece 110 of the electronic stethoscope 100 will be described. Here, the operation of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a will be described as an example, but the basic operation examples of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b are similar.

[0097] As shown in Figures 4(a) and 4(b), the chestpiece 110 is used in contact with the biological surface 320 of the subject. Therefore, the biological surface 320, the diaphragm 206, and the light-reflecting part 207 vibrate together. The vibration or displacement of the biological surface 320 occurs in response to bodily movements such as heartbeat and respiration of the person having the biological surface 320. The chestpiece 110 detects the displacement of the upper surface of the light-reflecting part 207 in the z-axis direction. The electronic auscultation device 100 can acquire vibration data of the biological surface 320, including body temperature, by optically detecting the displacement of the light-reflecting part 207 using the chestpiece 110.

[0098] Figure 4(a) shows a cross-sectional view of the chestpiece 110 when the diaphragm 206 is flat. The first aperture portion 209a and the third aperture portion 210a are arranged so that when the diaphragm 206 is flat, more first reflected light 212a is received by the first light-receiving element 204a compared to when the diaphragm 206 is displaced (deformed). When the diaphragm 206 is flat, the amount of displacement of the center 206e of the diaphragm 206 in the z-axis direction is 0, and when the diaphragm 206 is deformed (displaced), the amount of displacement of the center 206e in the z-axis direction is not 0.

[0099] The first aperture section 209a and the third aperture section 210a form an optical path through which light emitted from the first light-emitting element 202a is directed toward the first light-receiving element 204a via the light-reflecting section 207. The second aperture section 209b and the fourth aperture section 210b form an optical path through which light emitted from the second light-emitting element 202b is directed toward the second light-receiving element 204b via the light-reflecting section 207. In other words, the first aperture section 209a and the third aperture section 210a can be called optical path forming sections that form optical paths relating to the first light-emitting element 202a and the first light-receiving element 204a. The second aperture section 209b and the fourth aperture section 210b can also be called optical path forming sections that form optical paths relating to the second light-emitting element 202b and the second light-receiving element 204b. Furthermore, the first aperture section 209a is an example of a first optical path forming section that forms a first optical path from the light-emitting element 202 toward the first region of the light-reflecting section 207 (reflective surface). The second aperture portion 209b is an example of a second optical path forming portion that forms a second optical path from the light-emitting element 202 toward the second region of the light-reflecting portion 207 (reflecting surface). In this embodiment, the optical path forming portion is part of the holding member 201, but at least a part of the optical path forming portion may be made of a member other than the holding member 201.

[0100] The first light-receiving element 204a amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the first light-receiving circuit board 205a generates an output value obtained by converting the photocurrent output from the first light-receiving element 204a into a voltage, and outputs this output value to the outside of the chestpiece 110. In this embodiment, the displacement signal refers to the output value of the first light-receiving circuit board 205a and / or the second light-receiving circuit board 205b that reflects the state and deformation of the diaphragm 206 at any given time.

[0101] Figure 4(b) shows a cross-sectional view of the chestpiece 110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the first light-emitting element 202a to the upper surface of the light-reflecting portion 207 decreases. As the biological surface 320 is displaced, the region 207a of the light-reflecting portion 207 to which the first incident light 211a reaches is also displaced. Furthermore, as the region 207a of the light-reflecting portion 207 is displaced, the path through which the first reflected light 212a passes also shifts upward, resulting in at least a portion of the first reflected light 212a falling outside the aperture range of the third aperture portion 210a. As a result, the amount of light from the first reflected light 212a reaching the first photodetector 204a decreases, and the value of the displacement signal generated by the first photodetector circuit board 205a changes. In this embodiment, as the amount of light incident on the first photodetector 204a per unit time decreases, the value of the displacement signal decreases (the voltage value decreases). As shown in Figure 4(b), if the first reflected light 212a does not reach the first photodetector 204a at all, the value of the displacement signal ideally becomes zero.

[0102] Thus, the chestpiece 110 is configured such that the amount of light reaching the first light-receiving element 204a changes in accordance with the displacement of the biological surface 320, the diaphragm 206, and the light-reflecting part 207. Since the light-reflecting part 207 is displaced in conjunction with the displacement of the biological surface 320, the displacement signal generated by the first light-receiving circuit board 205a represents the displacement of the biological surface 320.

[0103] Similarly, the chestpiece 110 is configured such that the amount of light reaching the second light-receiving element 204b changes in accordance with the displacement of the biological surface 320, the diaphragm 206, and the light-reflecting part 207. Since the light-reflecting part 207 displaces in conjunction with the displacement of the biological surface 320, the displacement signal generated by the second light-receiving circuit board 205b represents the displacement of the biological surface 320. [Principle of optical displacement detection]

[0104] Figures 14(a) to 16 are used to supplement the principle of how the displacement signal changes in accordance with the displacement of the diaphragm 206. Figures 14(a) to 16 and the following explanation apply to the detection mechanism including the first light-emitting element 202a and the first light-receiving element 204a, and the detection mechanism including the second light-emitting element 202b and the second light-receiving element 204b, respectively. In other words, "light-emitting element 202", "light-receiving element 204", "aperture section 209", "aperture section 210", "incident light 211", and "reflected light 212" in the following explanation can be read as the first light-emitting element 202a, the first light-receiving element 204a, the first aperture section 209a, the third aperture section 210a, the first incident light 211a, and the first reflected light 212a, respectively. Furthermore, in the following description, "light-emitting element 202," "light-receiving element 204," "aperture section 209," "aperture section 210," "incident light 211," and "reflected light 212" may be read as the second light-emitting element 202b, the second light-receiving element 204b, the second aperture section 209b, the fourth aperture section 210b, the second incident light 211b, and the second reflected light 212b, respectively.

[0105] Figures 14(a) and 14(b) show the diaphragm 206 in an unpressed state (i.e., flat), while Figures 15(a) and 15(b) show the diaphragm 206 deformed upward by being pressed by the biological surface 320. In Figures 14(a) and 15(a), the lower side schematically shows a cross-section of the chestpiece 110, and the upper side schematically shows a planar layout of the chestpiece 110 viewed from above. In the planar layout, only the light-emitting element 202, light-receiving element 204, light-reflecting part 207, aperture parts 209 and 210 are shown. Figures 14(b) and 15(b) are perspective views focusing on the light-emitting element 202, light-receiving element 204, light-reflecting part 207, light-shielding wall 304, and light-shielding wall 305.

[0106] As shown in Figures 14(a) to 15(b), a portion of the light emitted by the light-emitting element 202 is blocked by the light-shielding wall 304 surrounding the opening 306 of the aperture portion 209 and does not reach the light-reflecting portion 207. In addition, at least a portion of the light specularly reflected by the light-reflecting portion 207 is blocked by the light-shielding wall 305 surrounding the opening 307 of the aperture portion 210, depending on the position of the light-reflecting portion 207, and does not reach the light-receiving element 204.

[0107] In this embodiment, both the opening 306 of the aperture portion 209 and the opening 307 of the aperture portion 210 are rectangular. In the following description, of the four sides of each of the openings 306 and 307, the side that is parallel to the diaphragm 206 and closer to the diaphragm 206 will be referred to as the bottom side, and the side that is parallel to the diaphragm 206 and further away from the diaphragm 206 will be referred to as the top side. Also, of the four sides of each of the openings 306 and 307, the side to the left when viewed from the light-emitting element 202 will be referred to as the left side, and the side to the right when viewed from the light-emitting element 202 will be referred to as the right side.

[0108] In Figures 14(a) to 15(b), the incident light 211 and reflected light 212 represent the beams of light that reach the photodetector 204. In Figure 14(b), some of the light 310 emitted from the light-emitting element 202 passes through the opening 306 of the light-shielding wall 304 and through the path 311 where it is reflected by the light-reflecting part 207, but it is blocked by the portion of the light-shielding wall 305 above the opening 307 and does not reach the photodetector 204.

[0109] As shown in Figures 14(a) and 14(b), the portion of the light-reflecting part 207 that reaches the incident light 211 when the diaphragm 206 is not pressed by the biological surface 320 is referred to as the effective range 300. The effective range 300 is the portion of the light-reflecting part 207 that reflects light that reaches the light-receiving element 204. When the diaphragm 206 is not pressed by the biological surface 320, the effective range 300 is equal to the range to which light from the light-emitting element 202 reaches. In this embodiment, the effective range 300 is a rectangular area. The outer periphery of the effective range 300 is referred to as the boundary line of the effective range 300. The boundary line of the effective range 300 is located between the effective range 300 and the area outside the effective range 300. In the following description, a part of the boundary line is also referred to as the boundary line.

[0110] Of the four line segments that constitute the boundary of the effective range 300, the line segment that includes the position furthest from the light-emitting element 202 in the x-axis direction is denoted as the far boundary line 300a. The portion of the incident light 211 that reaches the far boundary line 300a is denoted as the far incident light 211f. The far incident light 211f means that it includes the portion of the optical path from the light-emitting element 202 to the light-reflecting part 207 that is the longest. The angle of incidence of the incident light 211 to the light-reflecting part 207 is at its maximum value of 303a at the position on the far boundary line 300a.

[0111] Of the four line segments that constitute the boundary of the effective range 300, the line segment containing the position closest to the light-emitting element 202 in the x-axis direction is denoted as the near boundary 300b. The portion of the incident light 211 that reaches the near boundary 300b is denoted as the near incident light 211n. The near incident light 211n means that it includes the portion where the optical path from the light-emitting element 202 to the light-reflecting section 207 is the shortest. The angle of incidence of the incident light 211 to the light-reflecting section 207 is at its minimum value of 303b at the position on the near boundary 300b. Of the light emitted from the light-emitting element 202, the light that is not included between the far incident light 211f and the near incident light 211n is attenuated by being reflected multiple times by the light-shielding wall 304.

[0112] Of the four line segments that constitute the boundary of the effective range 300, the two line segments other than the far boundary line 300a and the near boundary line 300b are referred to as the lateral boundary lines 300c and 300d. The lateral boundary line 300c is located to the right of the effective range 300 as viewed from the light-emitting element 202, and the lateral boundary line 300d is located to the left of the effective range 300 as viewed from the light-emitting element 202.

[0113] As shown in Figures 14(a) and 14(b), the region of the light-receiving element 204 formed by the reflected light 212 specularly reflected by the light-reflecting portion 207 is referred to as the light-illuminated region 301. The light-illuminated region 301 is the portion of the light-receiving element 204 that reaches the light emitted from the light-emitting element 202 and specularly reflected by the light-reflecting portion 207. In addition to the light specularly reflected by the light-reflecting portion 207, scattered light may also reach the light-receiving element 204, but in this embodiment, the region formed by specularly reflected light is defined as the light-illuminated region. The amount of light reaching the light-receiving element 204 is proportional to the area of ​​the light-illuminated region 301. In this embodiment, the light-illuminated region 301 is a rectangular region. The outer periphery of the light-illuminated region 301 is referred to as the boundary line of the light-illuminated region 301. The boundary line of the light-illuminated region 301 is located between the light-illuminated region 301 and the region other than the light-illuminated region 301.

[0114] Of the four line segments that constitute the boundary of the light-irradiated area 301, the line segment formed by light that is narrowed by the aperture 209 and specularly reflected by the light-reflecting part 207 is referred to as the lower boundary line 301a. Of the four line segments that constitute the boundary of the light-irradiated area 301, the line segment on the opposite side of the lower boundary line 301a is referred to as the upper boundary line 301b. The lower boundary line 301a is an example of a boundary line formed by light that is narrowed by the aperture 209 and specularly reflected by the light-reflecting part 207. The lower boundary line 301a is a boundary line that moves in accordance with the displacement of the contact surface 206a, as will be described later.

[0115] In this embodiment, the area of ​​the light-irradiated region 301 changes as the lower boundary line 301a moves, and the output of the light-receiving element 204 changes. This allows the displacement of the object to be measured. The upper boundary line 301b is an example of a boundary line that does not move in response to the displacement of the contact surface 206a and whose length does not change even if the contact surface 206a is displaced. Of the four line segments that constitute the boundary of the light-irradiated region 301, the two line segments other than the lower boundary line 301a and the upper boundary line 301b are referred to as the lateral boundary lines 301c and 301d. The lateral boundary line 301c is located to the right of the light-irradiated region 301 as viewed from the light-emitting element 202, and the lateral boundary line 301d is located to the left of the light-irradiated region 301 as viewed from the light-emitting element 202. The lateral boundary lines 301c and 301d are examples of boundary lines that do not move in response to the displacement of the contact surface 206a and whose length changes when the contact surface 206a is displaced, as will be described later.

[0116] Light passing through the aperture 306 along its upper edge is specularly reflected by the light reflecting section 207 and then reaches the lower boundary line 301a of the light-illuminating area 301 of the light-receiving element 204 without being blocked by the light-shielding wall 305. Therefore, the upper edge of the aperture 306 defines the lower boundary line 301a of the light-illuminating area 301. On the other hand, light passing through the aperture 306 along its lower edge is specularly reflected by the light reflecting section 207 and then blocked by the light-shielding wall 305, and does not reach the light-receiving element 204. Therefore, the lower edge of the aperture 306 does not define the light-illuminating area 301. Consequently, the near incident light 211n is not stopped by the aperture section 209. Alternatively, the light passing through the aperture 306 along its lower edge may be specularly reflected by the light reflecting section 207 and then reach the light-receiving element 204 without being blocked by the light-shielding wall 305. In this case, the lower edge of the aperture 306 defines the light irradiation area 301. In this configuration, the displacement signal remains constant from zero to a predetermined value as the displacement of the diaphragm 206 decreases. Subsequently, when the lower edge of the aperture 306 no longer defines the light irradiation area 301, the displacement signal begins to decrease monotonically.

[0117] Light that passes through the aperture 306 and is specularly reflected by the light reflecting section 207, and then passes through the aperture 307 along its upper edge, reaches the upper boundary line 301b of the light-illuminating area 301 of the light-receiving element 204. Therefore, the upper edge of the aperture 307 defines the upper boundary line 301b of the light-illuminating area 301. In other words, the upper edge of the aperture 307 is an example of an aperture that narrows the light specularly reflected by the light reflecting section 207. On the other hand, because it is blocked by the light-shielding wall 304, light does not pass through the portion along the lower edge of the aperture 307. Therefore, the lower edge of the aperture 307 does not define the light-illuminating area 301.

[0118] As shown in Figure 14(a), the lateral boundary lines 301c and 301d of the light-irradiated area 301 are defined by the right and left sides of the aperture 307. Alternatively, the lateral boundary lines 301c and 301d of the light-irradiated area 301 may be defined by the right and left sides of the aperture 306.

[0119] The reflected light of the far incident light 211f is referred to as the lower end reflected light 212f. The lower end reflected light 212f is the light that is located furthest down in the z-axis direction of the reflected light 212 (i.e., the part closest to the diaphragm 206). The lower end reflected light 212f reaches the lower boundary line 301a of the light irradiation region 301. The lower boundary line 301a is formed by light that is narrowed by the aperture portion 209 and specularly reflected by the light reflection portion 207. The lower end reflected light 212f is separated from each side of the aperture 307. That is, the lower end reflected light 212f is not narrowed by the aperture portion 210.

[0120] In the configurations of Figures 14(a) and 14(b), the lower boundary line 301a includes the position in the light irradiation region 301 that is closest to the diaphragm 206 in the direction normal to the diaphragm 206 (i.e., the z-axis direction) when the diaphragm 206 is not being pressed by the biological surface 320. Furthermore, in the configurations of Figures 14(a) and 14(b), the lower boundary line 301a includes the position in the light irradiation region 301 where the light with the maximum reflection angle at the light reflecting portion 207 reaches. This maximum reflection angle is equal to the maximum incident angle 303a. Moreover, in the configurations of Figures 14(a) and 14(b), the lower boundary line 301a includes the position furthest from the light-emitting element 202 in a plan view relative to the diaphragm 206 when it is not being pressed.

[0121] The reflected light of the near incident light 211n is represented as the upper end reflected light 212n. The upper end reflected light 212n is the light that is located furthest up in the z-axis direction of the reflected light 212 (i.e., the part furthest from the diaphragm 206). The upper end reflected light 212n reaches the upper boundary line 301b of the light irradiation region 301. In the configurations of Figures 14(a) and 14(b), the upper boundary line 301b includes the position in the light irradiation region 301 that is furthest from the diaphragm 206 in the direction normal to the diaphragm 206 (i.e., in the z-axis direction) when the diaphragm 206 is not pressed. Also, in the configurations of Figures 14(a) and 14(b), the upper boundary line 301b includes the position in the light irradiation region 301 that reaches the light with the minimum reflection angle at the light reflecting part 207. This minimum reflection angle is equal to the minimum incident angle 303b. Furthermore, in the configurations of Figures 14(a) and 14(b), the upper boundary line 301b includes the position closest to the light-emitting element 202 in a plan view relative to the diaphragm 206 when it is not being pressed.

[0122] As shown in Figures 15(a) and 15(b), when the diaphragm 206 is pressed by the biological surface 320, the positions of the effective range 300, the far boundary line 300a, the near boundary line 300b, the light irradiation area 301, the lower boundary line 301a, and the upper boundary line 301b change. Of the reflected light 212, the portion furthest from the light-emitting element 202 in the x-axis direction is called the lower end reflected light 212f. The lower end reflected light 212f reaches the lower boundary line 301a of the light irradiation area 301. As described above, the lower boundary line 301a is defined by the upper edge of the opening 306 of the aperture portion 209 on the light-emitting element 202 side. The lower boundary line 301a moves in accordance with the displacement of the contact surface 206a due to the elastic deformation of the diaphragm 206, and as a result, the area of ​​the light irradiation area 301 changes, and the output of the light-receiving element 204 also changes, as will be described later.

[0123] The lower boundary line 301a is displaced by a displacement ratio G with respect to the displacement of the diaphragm 206. Similarly, the position where the part of the reflected light 212 that is furthest from the light-emitting element 202 (in three-dimensional space, regardless of the x-axis direction) reaches the photodetector 204 is also displaced by a displacement ratio G. The displacement ratio G has a value corresponding to the angle of incidence of the incident light 211 to the light-reflecting part 207 and the angle of the light-receiving surface of the photodetector 204 with respect to the light-reflecting part 207. The chestpiece 110 may be configured such that the displacement ratio G is greater than 1.5, or it may be configured such that the displacement ratio G is greater than 2.

[0124] As shown in Figures 14(a) to 15(b), the upper boundary line 301b is defined by the portion of the light-shielding wall 305 above the reflected light 212, and is a boundary line that does not move in accordance with the displacement of the contact surface 206a and whose length does not change even if the contact surface 206a is displaced. The portion of the light-shielding wall 304 below the incident light 211 does not need to block the light emitted from the light-emitting element 202. For example, the portion of the light-shielding wall 304 below the incident light 211 does not need to be provided. Also, the lower boundary line 301a is defined by the portion of the light-shielding wall 304 above the incident light 211. Therefore, the portion of the light-shielding wall 305 below the reflected light 212 does not need to block the light specularly reflected by the light-reflecting portion 207. For example, the portion of the light-shielding wall 305 below the reflected light 212 does not need to be provided.

[0125] Referring to Figure 16, the changes in the light-irradiated area 301 formed by the reflected light 212 that reaches the light-receiving surface of the light-receiving element 204 will be explained. Figure 16 shows a plan view of the light-receiving surface of the light-receiving element 204. The left side of Figure 16 shows the position of the light-irradiated area 301 when the diaphragm 206 is not pressed. The right side of Figure 16 shows the position of the light-irradiated area 301 when the diaphragm 206 is pressed by the biological surface 320.

[0126] To illustrate direction, the coordinate system CS' is shown in Figure 16. The coordinate system CS' is a two-dimensional Cartesian coordinate system with mutually orthogonal x' and y' axes. The y' axis coincides with the y axis of the coordinate system CS. The x' axis is parallel to the xz plane of the coordinate system CS. In the following explanation, the positive x' axis direction is referred to as the upper side, and the negative x' axis direction is referred to as the lower side.

[0127] The surface of the light-receiving element 204 that faces the internal space 213 becomes the light-receiving surface. The light-receiving element 204 detects the amount of light that reaches the light-receiving surface. As described above, in this embodiment, the light-receiving element 204 is a single light-receiving element. A line sensor or an area sensor may be used instead of a single light-receiving element. The light-receiving surface may have a rectangular shape. Of the four sides of the light-receiving surface, the side that is parallel to the diaphragm 206 and closer to the diaphragm 206 is represented as side 204f.

[0128] The area of ​​the light-irradiated region 301 is defined by the lower boundary line 301a, the upper boundary line 301b, and the lateral boundary lines 301c and 301d. As shown in Figure 16, the lower boundary line 301a of the light-irradiated region 301 changes in the x' axis direction in accordance with the displacement of the contact surface 206a. On the other hand, the upper boundary line 301b, the lateral boundary lines 301c and 301d hardly move in accordance with the displacement of the contact surface 206a. Therefore, the area of ​​the light-irradiated region 301 changes in accordance with the movement of the lower boundary line 301a. The length of the upper boundary line 301b does not change even if the contact surface 206a is displaced. On the other hand, the lengths of the lateral boundary lines 301c and 301d change when the contact surface 206a is displaced.

[0129] When the area of ​​the light-illuminated region 301 changes, the signal output from the light-receiving element 204 also changes. Specifically, the greater the displacement of the contact surface 206a of the diaphragm 206 from a flat state, the shorter the distance between the lower boundary line 301a and the upper boundary line 301b (i.e., the lengths of the lateral boundary lines 301c and 301d), and the smaller the area of ​​the light-illuminated region 301. Therefore, the greater the displacement of the diaphragm 206 from a flat state, the less light the light-receiving element 204 receives. Accordingly, the signal output from the light-receiving element 204 also becomes smaller. As shown in Figure 16, the amount of movement of the lower boundary line 301a accompanying the movement of the light-reflecting portion 207 is greater than the amount of movement of the upper boundary line 301b accompanying the movement of the light-reflecting portion 207.

[0130] As shown in Figure 16, the change in the light-irradiated region 301 in the x' axis direction is greater than the change in the light-irradiated region 301 in the y' axis direction. Therefore, in order to increase the dynamic range of the photodetector 204, it is preferable to make the width of the photodetector 204 in the x' axis direction greater than the width of the photodetector 204 in the y' axis direction. More specifically, it is preferable that the width of the photodetector 204 in the x' axis direction be three times or more the width of the photodetector 204 in the y' axis direction.

[0131] Referring to Figure 17, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal is the voltage output from the light-receiving circuit board 205. Graph 400 in Figure 17 shows the relationship between the displacement of the biological surface 320 and the displacement signal. The horizontal axis of graph 400 represents the displacement of the biological surface 320, and the vertical axis represents the displacement signal generated by the light-receiving circuit board 205.

[0132] As described above, the displacement of the biological surface 320 is equal to the displacement of the upper surface of the light reflecting part 207. The displacement of the upper surface of the light reflecting part 207 is equal to the displacement of the diaphragm 206. As shown in Figure 16, as the displacement of the reflected light 212 increases, the amount of reflected light 212 that reaches the photodetector 204 decreases monotonically and linearly. Therefore, if the displacement of the biological surface 320 is d and the value of the displacement signal is S, then in the range d ≤ dmax, S can be expressed by the following equation: S = Vmax - k × d

[0133] In the above equation, Vmax is the value of the displacement signal when the displacement d is zero. Vmax is determined by the amount of light emitted by the light-emitting element 202 and the sensitivity of the photodetector 204. The sensitivity of the photodetector 204 is the amount of change in the output voltage per unit amount of light incident on the photodetector 204. Vmax is larger the higher the sensitivity of the photodetector 204. Also, Vmax is larger the higher the amount of light emitted by the light-emitting element 202. k is the amplification factor of the photodetector 204. k is also determined by the amount of light emitted by the light-emitting element 202 and the sensitivity of the photodetector 204. k is larger the higher the sensitivity of the photodetector 204. Also, k is larger the higher the amount of light emitted by the light-emitting element 202.

[0134] The displacement amount d at which the displacement signal S becomes zero is denoted as dmax. For example, dmax is 1 mm. As the displacement amount d of the biological surface 320 increases, the area of ​​the light-irradiated region 301 decreases and becomes zero. When the area of ​​the light-irradiated region 301 becomes zero, the displacement signal S also becomes zero. The displacement amount d at which the area of ​​the light-irradiated region 301 becomes zero is determined by the respective positions of the light-receiving element 204 and the aperture portion 210 with respect to the reflected light 212.

[0135] When the displacement d exceeds dmax, the reflected light 212 no longer reaches the photodetector 204, so even if the displacement d increases, the displacement signal S remains zero. Therefore, the chestpiece 110 is configured such that the displacement d is in the range of 0 or more and dmax or less within the range in which the vibration of the diaphragm 206 is expected (this is referred to as the operating range of the diaphragm 206). As shown in graph 400, the light-emitting element 202 and the photodetector 204 are arranged such that the amount of light reaching the photodetector 204 (amount of light received) changes monotonically in response to the movement of the light-reflecting part 207 in one direction within the operating range of the diaphragm 206. In the example of Figure 17, the photodetector 204 is arranged so that the amount of light received decreases monotonically, but the photodetector 204 may also be arranged so that the amount of light received monotonically increases.

[0136] In this embodiment, the light-emitting element 202 and the light-receiving element 204 are arranged such that all of the reflected light 212 reaches the light-receiving element 204 when the diaphragm 206 is flat. Alternatively, the light-emitting element 202 and the light-receiving element 204 may be arranged such that all of the reflected light 212 reaches the light-receiving element 204 when the diaphragm 206 is displaced below flat.

[0137] In the above embodiment, the normal to the light-receiving surface of the light-receiving element 204 is inclined with respect to the z-axis direction (i.e., the normal direction of the diaphragm 206). Alternatively, the normal to the light-receiving surface of the light-receiving element 204 may coincide with the z-axis direction. That is, the light-receiving surface will be parallel to the diaphragm 206.

[0138] In the chestpiece 110 according to the above embodiment, when a biological surface, which is an example of a subject, is in close contact with the diaphragm 206, a displacement signal is generated based on the amount of displacement of the biological surface 320, which vibrates integrally with the diaphragm 206. Therefore, for example, displacement of the biological surface 320 due to low-frequency vibrations of about 10 Hz can be detected with high accuracy. Such low-frequency vibrations are included in sounds (e.g., heart sounds) emitted by vibrations propagated from inside the body by the heartbeat. In the chestpiece 110, the displacement signal does not change unless the diaphragm 206 is displaced. Therefore, ambient noise and vibrations or accelerations due to the movement of the chestpiece 110 are not detected as noise, and a high S / N ratio output characteristic can be obtained. [Hardware configuration of the electronic stethoscope]

[0139] Refer to Figure 18 for an example of the hardware configuration of the electronic stethoscope 100. The electronic stethoscope 100 comprises the chestpiece 110 described above and a sound output unit 510. The sound output unit 510 is realized by a plurality of circuit elements mounted on a circuit board included in the gripping unit 120. The plurality of circuit elements include a processor. The processor constituting the sound output unit 510 transmits a sound signal based on the displacement signal generated by the chestpiece 110 to an external sound output device. The sound signal transmitted by the sound output unit 510 represents the biological sound of a living organism (e.g., a human) having a biological surface 320, and is therefore also called a biosound. The sound signal is transmitted to a sound output device 520 such as earphones or headphones. At the same time as transmitting the sound signal to the sound output device 520, it is also transmitted to a computer 530 (e.g., a personal computer, smartphone, tablet, etc.). Users such as doctors, nurses, and public health nurses can listen to the biological sound represented by the digitally converted sound signal using the sound output device 520 or the computer 530. The sound output device 520 is either a wired or wireless earphone or headphones.

[0140] The sound output unit 510 has the components shown in Figure 18. The sound output unit 510 is compatible with the earphones or headphones described above and is capable of transmitting sound signals via both wireless and wired communication. The following describes the process by which the sound output device 520 outputs sound signals via wired communication. The displacement signal output from the chestpiece 110 is filtered and amplified by the filter / amplifier 518 and supplied to the A / D converter 511 and amplifier 515, respectively. The amplifier 515 further amplified the output from the filter / amplifier 518 and supplied it to the wired communication unit 517. The wired communication unit 517 provided the amplified sound signal to the sound output device 520. The wired communication unit 517 is, for example, a 3.5 mm AUX terminal. The amplification gain of the amplifier 515 is adjusted by the volume control unit 516. The sound output device 520 may be considered as part of the electronic stethoscope 100. In this case, the electronic stethoscope 100 includes a chestpiece 110, a gripping part 120, and a sound output device 520.

[0141] Next, the processing for the sound output device 520 to output an audio signal via wireless communication will be described. The A / D converter 511 digitizes the output from the filter / amplifier 518. The digital displacement signal is then amplified by the amplifier 512 and supplied to the encoder 513. The encoder 513 generates audio data for wireless communication by performing signal processing such as data compression and encoding on the amplified audio signal. The processing order of the amplifier 512 and encoder 513 may be reversed. Subsequently, the wireless communication unit 514, which conforms to a wireless communication standard such as Bluetooth®, provides the processed audio data to the sound output device 520. The amplification gain of the amplifier 512 is adjusted by the volume control unit 516. The electronic stethoscope 100 described above is an example in which an audio signal can be output by both wireless and wired communication, but it may also be possible to output an audio signal by only one of these communications.

[0142] The transmission of an audio signal to the computer 530 is the same as the transmission of an audio signal to the sound output device 520. The computer 530 can also visually display waveform data generated based on the audio signal. The waveform data may be generated by the computer 530 or by the electronic stethoscope 100. In addition, some or all of the signal processing and sound output processing by the electronic stethoscope 100 may be performed by an external device (for example, the sound output device 520 or the computer 530).

[0143] In this disclosure, "detection device" refers to a device having at least a diaphragm, a light-emitting unit, and a light-receiving unit, capable of generating a signal (displacement signal described later) corresponding to the displacement of a biological surface. Therefore, the chestpiece 110 of this embodiment is an example of a "detection device". Furthermore, the electronic auscultation device 100 of this embodiment, in which the chestpiece 110 and the gripping unit 120 are integrated, can also be called a detection device as a whole. If the chestpiece 110 is separable from the gripping unit 120 (detachable, replaceable), the chestpiece 110 in the state separated from the gripping unit 120 may also be referred to as a detection device.

[0144] Furthermore, in this disclosure, "electronic stethoscope" refers to a device having at least a detection device and a sound output unit that outputs a signal (sound signal) to a sound output device to emit sound based on a signal (displacement signal) generated by the detection device. The electronic stethoscope 100 according to this embodiment comprises a chestpiece 110 and a sound output unit 510 mounted inside a gripping unit 120. The detection device and the sound output unit do not necessarily have to be configured as a single unit. For example, the chestpiece 110 may be attached to a subject, while the sound output unit 510 remains on a desk and receives the displacement signal by communicating with the chestpiece 110 via wired or wireless means.

[0145] The electronic auscultation device 100 can accurately detect the displacement of the biological surface 320 in relation to vibrations across a wide frequency range of the biological surface 320. Therefore, the electronic auscultation device 100 enables good auscultation of both relatively low-frequency biological sounds such as heart sounds emitted by the body due to heartbeat, and relatively high-frequency biological sounds emitted by the body due to respiration. Respiratory sounds are biological vibrations that include a frequency band (first frequency band) containing components in the range of 500 Hz to 1 kHz, for example. Heart sounds are biological vibrations that include a frequency band (second frequency band) containing components in the range of 30 Hz to 300 Hz, for example.

[0146] A mode switching button 123c is provided on the operating unit 123 of the electronic stethoscope 100. When the mode switching button 123c is pressed, the auscultation mode of the electronic stethoscope 100 switches between a mode suitable for auscultation of heart sounds (hereinafter referred to as "heart sound mode") and a mode suitable for auscultation of breath sounds (hereinafter referred to as "breath sound mode"). The electronic stethoscope 100 may have auscultation modes other than the heart sound mode and the breath sound mode. When auscultating heart sounds, the user operates the mode switching button 123c provided on the operating unit 123 to select the heart sound mode, which is one of the auscultation modes. On the other hand, when auscultating breath sounds, the user operates the mode switching button 123c provided on the operating unit 123 to select the breath sound mode, which is one of the auscultation modes.

[0147] The control unit 123 is provided with volume adjustment buttons (123a, 123b) for adjusting the gain of the displacement signal output by the electronic stethoscope 100. The volume adjustment buttons (123a, 123b) are used to adjust the volume of the sound output by the electronic stethoscope 100. Furthermore, the display unit 122 of the electronic stethoscope 100 is equipped with an LED as an indicator to show whether the current auscultation mode is heart sound mode or respiratory sound mode. The user can visually confirm whether the operating mode is heart sound mode or respiratory sound mode by the state of illumination of this LED. Note that heart sound mode and respiratory sound mode are examples of auscultation modes.

[0148] In this embodiment, for example, when the respiratory sound mode is selected, only the first light-emitting circuit board 203a (first light-emitting unit) and the first light-receiving circuit board 205a (first light-receiving unit) are driven in the chestpiece 110. That is, the first light-emitting element 202a emits light, and a displacement signal corresponding to the photocurrent output by the first light-receiving element 204a is output to the sound output unit 510, while the light emission of the second light-emitting element 202b is stopped, and the state of the second light-receiving element 204b is not reflected in the displacement signal. On the other hand, for example, when the heart sound mode is selected, only the second light-emitting circuit board 203b (second light-emitting unit) and the second light-receiving circuit board 205b (second light-receiving unit) are driven in the chestpiece 110. In other words, the second light-emitting element 202b emits light, and a displacement signal corresponding to the photocurrent output by the second photo-receiving element 204b is output to the sound output unit 510, while the first light-emitting element 202a stops emitting light, and the state of the first photo-receiving element 204a is not reflected in the displacement signal.

[0149] The respiratory sound mode is an example of a first mode that detects biological vibrations in a first frequency band, and the heart sound mode is an example of a second mode that detects biological vibrations in a second frequency band lower than the first frequency band. Biological vibrations other than respiratory sounds may be detected in the first mode, and biological vibrations other than heart sounds may be detected in the second mode.

[0150] However, the method of mode selection and the control manner of the light-emitting and light-receiving units in each mode are not limited to this. For example, when the heart sound mode or respiratory sound mode is selected, both the pair of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a (first optical detection pair) and the pair of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b (second optical detection pair) may be driven. In this case, a first displacement signal based on the output of the first light-receiving element 204a and a second displacement signal based on the output of the second light-receiving element 204b may be transmitted in parallel to the sound output unit 510, and a sound signal may be generated by mixing in the sound output unit 510. [Relationship between diaphragm displacement and reflected light axis displacement]

[0151] Here, with reference to Figures 5(a) and 5(b), the relationship between the displacement of the biological surface 320 and the displacement of the optical axis position of the reflected light on the light-receiving surfaces of the first light-receiving element 204a and the second light-receiving element 204b will be explained. Figure 5(a) is a schematic diagram showing the positional relationship between the first light-emitting element 202a, the upper surface of the light-reflecting part 207, and the first light-receiving element 204a. Figure 5(b) is a schematic diagram showing the positional relationship between the second light-emitting element 202b, the upper surface of the light-reflecting part 207, and the second light-receiving element 204b.

[0152] In Figure 5(a), position 401 indicates the reference position of the upper surface of the light-reflecting portion 207 in the z-axis direction. In this embodiment, the reference position is the position of the upper surface of the aforementioned region 207a of the light-reflecting portion 207 when the diaphragm 206 is flat. Position 402 indicates the position where the upper surface of the light-reflecting portion 207 is displaced upward by a certain displacement amount d2 from position 401. Since the displacement amount d2 of the light-reflecting portion 207 is small compared to the diameter of the diaphragm 206, even when the upper surface of the light-reflecting portion 207 is at position 402, the region 207a of the upper surface of the light-reflecting portion 207 is assumed to be flat. Furthermore, in the following description, the displacement amount d2 is assumed to be a non-negative value regardless of whether the direction of displacement is in the positive or negative direction of the z-axis.

[0153] In Figure 5(a), the first incident optical axis 403a represents the optical axis of the first incident light 211a. The angle of incidence of the first incident optical axis 403a with respect to the light reflecting section 207 is denoted as the first angle of incidence, and is represented by θa. The first angle of incidence θa is defined by the angle between the first incident optical axis 403a and the normal to the upper surface of the light reflecting section 207. The optical axis of the first reflected light 212a when the upper surface of the light reflecting section 207 is at position 401 is defined as the first reflected optical axis 404a. The optical axis of the first reflected light 212a when the upper surface of the light reflecting section 207 is at position 402 is defined as the second reflected optical axis 405a. Since the first incident light 211a is specularly reflected at the upper surface of the light reflecting section 207, the first angle of reflection of the first reflected light 212a is also θa. The first reflected optical axis 404a and the second reflected optical axis 405a are parallel to each other. Furthermore, when the angle of incidence of the first reflected light 212a to the first light-receiving element 204a is φa, in this embodiment φa is 0°, but φa may be other than 0°.

[0154] The first displacement amount d3a is defined as the amount of displacement of the optical axis of the first reflected light 212a on the light-receiving surface of the first light-receiving element 204a when the upper surface of the light-reflecting part 207 is displaced from position 401 (reference position) to position 402. The first displacement amount d3a can also be expressed as the distance from the position where the first reflected light axis 404a intersects the light-receiving surface of the first light-receiving element 204a to the position where the second reflected light axis 405a intersects the light-receiving surface of the first light-receiving element 204a.

[0155] The ratio of the first displacement d3a to the displacement d2 is expressed as the first displacement ratio Ga. In this case, the following relationships, Equations 1 and 2, hold: d3a = Ga × d2 …(Equation 1) Ga = 2 × sinθa / cosφa …(Equation 2)

[0156] From Equation 2, it can be seen that even if the displacement d2 of the light reflecting part 207 is the same, the larger the incident angle θa, the larger the first displacement magnification Ga becomes, and the larger the incident angle φa, the larger the first displacement magnification Ga becomes. In other words, the larger the first incident angle θa, the larger the first displacement d3a becomes. In particular, when the incident angle φa is 0°, that is, when the first reflected optical axis 404a and the second reflected optical axis 405a are perpendicular to the light-receiving surface of the first light-receiving element 204a, Equation 2 can be rewritten as follows: Ga = 2 × sinθa … (Equation 23)

[0157] In Figure 5(b), the second incident optical axis 403b represents the optical axis of the second incident light 211b. The angle of incidence of the second incident optical axis 403b with respect to the light reflecting section 207 is defined as the second incident angle, and is represented by θb. The second incident angle θb is defined by the angle between the second incident optical axis 403b and the normal to the upper surface of the light reflecting section 207. The optical axis of the second reflected light 212b when the upper surface of the light reflecting section 207 is at position 401 is defined as the third reflected optical axis 404b. The optical axis of the second reflected light 212b when the upper surface of the light reflecting section 207 is at position 402 is defined as the fourth reflected optical axis 405b. Since the second incident light 211b is specularly reflected at the upper surface of the light reflecting section 207, the second reflection angle of the second reflected light 212b is also θb. The third reflected optical axis 404b and the fourth reflected optical axis 405b are parallel to each other. Furthermore, when the angle of incidence of the second reflected light 212b to the second light-receiving element 204b is φb, in this embodiment φb is 0°, but φb may be other than 0°.

[0158] The second displacement amount d3b is the amount of displacement of the optical axis of the second reflected light 212b on the light-receiving surface of the second light-receiving element 204b when the upper surface of the light-reflecting part 207 is displaced from position 401 (reference position) to position 402. The second displacement amount d3b can also be expressed as the distance from the position where the third reflected light axis 404b intersects the light-receiving surface of the second light-receiving element 204b to the position where the fourth reflected light axis 405b intersects the light-receiving surface of the second light-receiving element 204b.

[0159] The ratio of the second displacement d3b to the displacement d2 is expressed as the second displacement ratio Gb. In this case, the following relationships, Equations 4 and 5, hold: d3b = Gb × d2 …(Equation 4) Gb = 2 × sinθb / cosφb …(Equation 5)

[0160] From Equation 5, it can be seen that even if the displacement d2 of the light reflecting part 207 is the same, the larger the incident angle θb, the larger the second displacement magnification Gb, and the larger the incident angle φb, the larger the second displacement magnification Gb. In other words, the larger the second incident angle θb, the larger the second displacement d3b. In particular, when the incident angle φa is 0°, that is, when the third reflected optical axis 404a and the fourth reflected optical axis 405a are perpendicular to the light-receiving surface of the first light-receiving element 204a, Equation 5 can be rewritten as follows: Gb = 2 × sinθb … (Equation 6)

[0161] As can be seen from equations 1 to 6 (especially equations 23 and 6), the larger the incident angle (θa, θb) of the incident optical axis with respect to the light reflecting part 207, the larger the displacement (d3a, d3b) of the reflected optical axis at the light receiving surface of the light receiving part.

[0162] In this embodiment, the first incident angle θa is set to be greater than the second incident angle θb. The following relationship holds between the first displacement ratio Ga and the second displacement ratio Gb: Ga > Gb ... (Equation 7) In other words, if the displacement of the biological surface 320 is the same, the displacement of the reflected light axis at the light-receiving surface of the first light-receiving element 204a (d3a) is greater than the displacement of the reflected light axis at the light-receiving surface of the second light-receiving element 204b (d3b).

[0163] Furthermore, in order to satisfy the relationship Ga > Gb, it is preferable that the incident angle φa of the reflected light axis to the first photodetector 204a is greater than or equal to the incident angle (φb or greater) of the reflected light axis to the second photodetector 204b (see Equations 2 and 5).

[0164] The displacement magnification value affects the detection range and sensitivity of the electronic stethoscope 100. The detection range (measurement range) is the range of vibration amplitudes of the biological surface 320 that the electronic stethoscope 100 can measure. Sensitivity (displacement resolution) is the smallest unit of displacement of the biological surface 320 that the electronic stethoscope 100 can measure. By setting an appropriate displacement magnification according to the amplitude of the biological sound being measured, a displacement signal that appropriately reflects the displacement of the biological surface 320 can be obtained.

[0165] In this embodiment, the displacement ratios (Ga, Gb) differ between the pair of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a and the pair of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b. In other words, the displacement ratios differ between the first optical detection pair and the second optical detection pair. Therefore, when measuring multiple types of biological sounds, an appropriate displacement ratio can be set for each optical detection pair according to the amplitude of the biological sound, enabling accurate detection of multiple types of biological sounds with a single electronic stethoscope.

[0166] Specifically, when detecting respiratory sounds with smaller amplitudes of biological vibration, it is preferable to use the first light-emitting element 202a and the first light-receiving element 204a, which have a large angle of incidence to the light-reflecting section 207. When detecting heart sounds with larger amplitudes of biological vibration, it is preferable to use the second light-emitting element 202b and the second light-receiving element 204b, which have a small angle of incidence to the light-reflecting section 207. This allows for a wider detection range when detecting heart sounds with large amplitudes and an increased sensitivity (resolution) when detecting respiratory sounds with small amplitudes. As a result, it becomes possible to accurately detect two types of biological sounds with a single electronic stethoscope.

[0167] In this embodiment, a detection method was described in which a light-emitting element that emits diffused light is used to extract a displacement signal from the change in the area that receives light from the photodetector. However, the detection method in an optical displacement detection mechanism is not limited to this. For example, when using a laser light source, a displacement signal may be generated based on the change in the position where the laser light is detected within the detection area (region where pixels are arranged) of the photodetector, which is a line sensor or area sensor. In that case as in this embodiment, the value of the displacement magnification changes according to the angle of incidence of light to the light reflecting part 207, and the same advantages as in this embodiment can be obtained by setting the first incident angle θa and the second incident angle θb to different values. [Relationship between the amount of displacement of the biological surface and the displacement signal]

[0168] Referring to Figure 6, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal represents the voltage output from the first light-receiving circuit board 205a and the second light-receiving circuit board 205b. The horizontal axis of Figure 6 represents the displacement d2 of the upper surface of the light-reflecting part 207 that is linked to the biological surface 320 (see also Figures 5(a) and 5(b)), and the vertical axis of Figure 6 represents the magnitude of the displacement signal generated by the first light-receiving circuit board 205a or the second light-receiving circuit board 205b. Graph 500a shows the value of the displacement signal generated by the first light-receiving circuit board 205a for each displacement d2 (Sda below), and graph 500b shows the value of the displacement signal generated by the second light-receiving circuit board 205b for each displacement d2 (Sdb below).

[0169] As described above, the displacement d2 of the upper surface of the light reflecting portion 207 corresponds to the displacement of the biological surface 320, and the displacements of the optical axes of the first reflected light 212a and the second reflected light 212b (d3a, d3b) are proportional to d2 (Equations 1 and 4). Furthermore, as explained using Figures 4(a) and 4(b), and Figures 5(a) and 5(b), as the first displacement d3a increases, the amount of light from the first reflected light 212a that reaches the first photodetector 204a decreases. Similarly, as the second displacement d3b increases, the amount of light from the second reflected light 212b that reaches the second photodetector 204b decreases. Here, it is assumed that the amount of light received by the first photodetector 204a decreases monotonically and linearly with respect to an increase in the first displacement d3a, and that the amount of light received by the second photodetector 204b decreases monotonically and linearly with respect to an increase in the second displacement d3b. In this case, the displacement signal values ​​Sda and Sdb generated by the first light-receiving circuit board 205a and the second light-receiving circuit board 205b can be expressed by the following equations 8 and 9: Sda = Vmax - k × d3a ... (Equation 8) Sdb = Vmax - k × d3b ... (Equation 9)

[0170] Here, Vmax is the value Sda of the displacement signal generated by the first light-receiving circuit board 205a and the second light-receiving circuit board 205b when the first displacement d3a and the second displacement d3b are zero (i.e., the displacement d2 of the biological surface 320 is zero). In other words, Vmax is the output of the first light-receiving circuit board 205a (second light-receiving circuit board 205b) when the first light-receiving element 204a (second light-receiving element 204b) is receiving light of maximum intensity. k is a coefficient determined by the amplification factor of the peripheral circuit (amplifier circuit) in the first light-receiving circuit board 205a and the second light-receiving circuit board 205b. In this embodiment, Vmax and k are assumed to be common between the first light-receiving circuit board 205a and the second light-receiving circuit board 205b, but these values ​​may be different from each other. Even in that case, the following explanation will not change in essence.

[0171] By substituting equations 1, 2, 4, and 5 mentioned above into equations 8 and 9, the following equations are obtained: Sda = Vmax - 2k × d² × sinθa / cosφa …(Equation 10) Sdb = Vmax - 2k × d² × sinθb / cosφb …(Equation 11)

[0172] As shown by graphs 500a and 500b in Figure 6, the displacement signal values ​​Sda and Sdb decrease monotonically and linearly as the displacement amount d2 of the biological surface 320 increases. The displacement amounts d2 at which the displacement signal values ​​Sda and Sdb become zero are denoted as dmaxa and dmaxb. When the displacement amount exceeds dmaxa, the first reflected light 212a no longer reaches the first photodetector 204a, so even if the displacement amount d2 increases further, the displacement signal value Sda remains zero. Similarly, when the displacement amount exceeds dmaxb, the second reflected light 212b no longer reaches the second photodetector 204b, so even if the displacement amount d2 increases further, the displacement signal value Sdb remains zero.

[0173] Therefore, the proportionality constant k, the incident angles θa, θb, and φa, φb, as well as the opening widths of the first and third aperture sections 209a and 210a, are set so that the displacement amount d2 falls within a range of dmax a or less, depending on the amplitude of the biological sound to be measured. In other words, for example, assuming the maximum amplitude of vibration of the biological surface 320 caused by breathing, the proportionality constant k, the first incident angle θa, and the incident angle φa are set so that this value is dmax a or less. Similarly, assuming the maximum amplitude of vibration of the biological surface 320 caused by the heartbeat, the proportionality constant k, the second incident angle θb, and the incident angle φb, as well as the opening widths of the second and fourth aperture sections 209b and 210b, are set so that this value is dmax b or less. This reduces the possibility that the biological sound may not be correctly detected due to the displacement amount of the biological surface 320 exceeding the detection range.

[0174] In equations 10 and 11, the coefficients of d2, 2k × sinθa / cosφa (=k × Ga) and 2k × sinθb / cosφb (=k × Gb), represent the sensitivity of the chestpiece 110. The angle of incidence (θa, θb) can take values ​​greater than 0° and less than 90°. The angles of incidence φa and φb can take values ​​between 0° and less than 90°. The larger the displacement ratios Ga and Gb, the higher the sensitivity of the chestpiece 110.

[0175] On the other hand, the diaphragm displacements dmax a and dmax b are expressed by the following equations obtained by substituting dmax a and dmax b into the left-hand sides of equations 10 and 11, respectively: dmax a = Vmax / (2k × sinθa / cosφa) ... (Equation 12) dmax b = Vmax / (2k × sinθb / cosφb) ... (Equation 13) The right-hand side of equation 12 may also be expressed as Vmax / (k × Ga). The right-hand side of equation 13 may also be expressed as Vmax / (k × Gb).

[0176] From equations 12 and 13, it can be seen that the values ​​of the displacement amount d2 that define the upper limit of the detection range (dmax a, dmax b) are inversely proportional to the displacement magnifications Ga and Gb. In other words, the smaller the displacement magnifications Ga and Gb, the larger dmax a and dmax b become, which are the upper limits of the measurable range of the displacement amount d2 of the diaphragm 206.

[0177] Based on the above, when detecting biological sounds with relatively large amplitudes, it is preferable to set the displacement magnifications Ga and Gb to small values ​​so that the displacement amount d2 does not exceed dmax a or dmax b. Conversely, when detecting biological sounds with relatively small amplitudes, it is preferable to set the displacement magnifications Ga and Gb to large values ​​in order to increase sensitivity. In other words, it is preferable to set the displacement magnifications Ga and Gb to the largest possible values ​​while avoiding the displacement amount d2 exceeding dmax a or dmax b (over-range).

[0178] According to the electronic stethoscope 100 of this embodiment, by arranging multiple sets of light-emitting and light-receiving units with different incident angles (θa, θb), appropriate displacement magnifications Ga and Gb can be set for multiple types of biological sounds. Therefore, multiple types of vibrations can be accurately detected with a single chestpiece 110 (detection device). Furthermore, multiple types of biological sounds can be accurately detected with a single electronic stethoscope 100. 《Second Embodiment》

[0179] Referring to Figures 7(a) to 12, the chestpiece 1110 of the electronic stethoscope 100 according to the second embodiment will be described. Hereinafter, elements with reference numerals common to the first embodiment will have basically the same configuration and function as those described in the first embodiment unless otherwise specified, and the parts that differ from the first embodiment will be mainly described.

[0180] First, the configuration of the chestpiece 1110 will be explained using Figures 7(a) and 7(b), and Figures 8(a) and 8(b). Figure 7(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line C-C in Figure 7(b). Figure 7(b) is a plan view (viewed in the negative z-axis direction) showing the internal layout of the chestpiece 1110. Figure 8(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line D-D in Figure 8(b). Figure 8(b) is a plan view showing the internal layout of the chestpiece 1110. Note that in Figures 7(b) and 8(b), the components other than the housing 208 of the chestpiece 1110 are shown by viewing the housing 208 through the housing 208.

[0181] As shown in Figures 7(a) to 8(b), the chestpiece 1110 includes a holding member 1201, light-emitting circuit boards (203a, 203b) including light-emitting elements (202a, 202b), and light-receiving circuit boards (205a, 205b) including light-receiving elements (204a, 204b). The chestpiece 1110 also includes a diaphragm 206 including a light-reflecting portion 207 and a housing 208.

[0182] The chestpiece 1110 according to this embodiment has a plurality of light-emitting units and a plurality of light-receiving units. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit. In other words, the chestpiece 1110 has a first light-emitting circuit board 203a as a first light-emitting unit, a second light-emitting circuit board 203b as a second light-emitting unit, a first light-receiving circuit board 205a as a first light-receiving unit, and a second light-receiving circuit board 205b as a second light-receiving unit.

[0183] The housing 208 houses the holding member 1201, the light-emitting circuit boards (203a, 203b), and the light-receiving circuit boards (205a, 205b) inside. Since the holding member 1201 has aperture sections (1209a, 1209b, 1210a, 1210b), the housing 208 can house the aperture sections inside. Note that the components of the chestpiece 1110 described here are just examples, and in addition to the components described above, the chestpiece 1110 may also have, for example, a circuit board on which circuit elements for controlling the operation of the chestpiece 1110 are mounted.

[0184] The first light-emitting circuit board 203a, which includes the first light-emitting element 202a, functions as a first light-emitting unit. The second light-emitting circuit board 203b, which includes the second light-emitting element 202b, functions as a second light-emitting unit. The first light-receiving circuit board 205a, which includes the first light-receiving element 204a, functions as a first light-receiving unit. The second light-receiving circuit board 205b, which includes the second light-receiving element 204b, functions as a second light-receiving unit.

[0185] The holding member 1201 holds the first light-emitting circuit board 203a, the second light-emitting circuit board 203b, the first light-receiving circuit board 205a, and the second light-receiving circuit board 205b. Each light-emitting circuit board and each light-receiving circuit board is fixed to the holding member 1201. These boards may be fixed to the holding member 201 using adhesive or fasteners such as screws.

[0186] The diaphragm 206 is held by the retaining member 1201. The contact surface 206a of the diaphragm 206 is exposed to the outside of the housing 208. Together with the housing 208, the diaphragm 206 forms part of the exterior of the chestpiece 1110 (the exterior of the electronic stethoscope 100).

[0187] The chestpiece 1110 has a first aperture portion 1209a and a second aperture portion 1209b that focus the light (diffuse light) emitted from the first light-emitting element 202a and the second light-emitting element 202b. The first aperture portion 1209a allows only a portion of the first incident light 211a emitted from the first light-emitting element 202a to enter the light-reflecting portion 207. The second aperture portion 1209b allows only a portion of the second incident light 211b emitted from the second light-emitting element 202b to enter the light-reflecting portion 207.

[0188] In the examples of Figures 7(a) and 8(a) and 8(b), the portion of the holding member 1201 through which the first incident light 211a passes corresponds to the first aperture portion 1209a. The portion of the holding member 1201 through which the second incident light 211b passes corresponds to the second aperture portion 1209b.

[0189] Furthermore, the chestpiece 1110 has a third aperture section 1210a and a fourth aperture section 1210b that narrow the light specularly reflected by the light reflecting section 207. The third aperture section 1210a suppresses diffusely reflected light from entering the first light-receiving element 204a, allowing only specularly reflected light from the light reflecting section 207 to reach the first light-receiving element 204a. The fourth aperture section 1210b suppresses diffusely reflected light from entering the second light-receiving element 204b, allowing only specularly reflected light from the light reflecting section 207 to reach the second light-receiving element 204b. In addition, the third aperture section 1210a and the fourth aperture section 1210b further narrow the specularly reflected light from the light reflecting section 207, allowing only a portion of the specularly reflected light to reach the first light-receiving element 204a and the second light-receiving element 204b.

[0190] In the examples of Figures 7(a) and 8(a) and 8(b), the portion of the holding member 1201 through which the first reflected light 212a passes corresponds to the third diaphragm portion 1210a (first opening). Also, the portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth diaphragm portion 1210b (second opening).

[0191] The first aperture portion 1209a can be called a first optical path forming portion that forms a first optical path from the light-emitting element 202 toward a first region of the light-reflecting portion 207 (reflecting surface). The second aperture portion 1209b can be called a second optical path forming portion that forms a second optical path from the light-emitting element 202 toward a second region of the light-reflecting portion 207 (reflecting surface).

[0192] A housing 208 is attached to the outer upper surface of the holding member 1201. The housing 208 covers the first light-emitting circuit board 203a and the second light-emitting circuit board 203b, as well as the first light-receiving circuit board 205a and the second light-receiving circuit board 205b, and also suppresses ambient noise from entering the housing 208.

[0193] Here, as shown in Figures 7(a) and 8(a), in this embodiment, the opening of the third aperture 1210a (first opening) is set to be narrower than the opening of the fourth aperture 1210b (second opening). In other words, the opening area of ​​the third aperture 1210a when viewed in the direction from the light reflecting part 207 toward the first light receiving element 204a is smaller than the opening area of ​​the fourth aperture 1210b when viewed in the direction from the light reflecting part 207 toward the second light receiving element 204b. Therefore, the area over which the first light receiving element 204a receives reflected light from the light reflecting part 207 is smaller than the area over which the second light receiving element 204b receives reflected light from the light reflecting part 207. The advantages of this configuration will be described later. [Example of operation of the electronic stethoscope according to the second embodiment]

[0194] Referring to Figures 9(a) and 9(b), and Figures 10(a) and 10(b), a basic example of operation of the chestpiece 1110 according to the second embodiment will be described. Figures 9(a) and 9(b) show an example of operation relating to the first light-emitting circuit board 203a and the first light-receiving circuit board 205a. Figures 10(a) and 10(b) show an example of operation relating to the second light-emitting circuit board 203b and the second light-receiving circuit board 205b.

[0195] Figure 9(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The first aperture portion 1209a and the third aperture portion 1210a are arranged so that, when the diaphragm 206 is flat, more of the first reflected light 212a is received by the first light-receiving element 204a compared to when the diaphragm 206 is displaced (deformed).

[0196] The first light-receiving element 204a amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the first light-receiving circuit board 205a generates an output value as a displacement signal by converting the photocurrent output from the first light-receiving element 204a into a voltage.

[0197] Figure 9(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the first light-emitting element 202a to the upper surface of the light-reflecting part 207 decreases. As the biological surface 320 is displaced, the region 207a of the light-reflecting part 207 to which the first incident light 211a reaches is also displaced. Furthermore, as the region 207a of the light-reflecting part 207 is displaced, the path through which the first reflected light 212a passes also shifts upward, resulting in at least a portion of the first reflected light 212a falling outside the aperture range of the third aperture part 1210a. As a result, the amount of light from the first reflected light 212a reaching the first photodetector 204a decreases, and the value of the displacement signal generated by the first photodetector circuit board 205a changes. In this embodiment, when the amount of light incident on the first light-receiving element 204a per unit time decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower).

[0198] Figure 10(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The second aperture portion 1209b and the fourth aperture portion 1210b are arranged so that, when the diaphragm 206 is flat, more second reflected light 212b is received by the second light-receiving element 204b compared to when the diaphragm 206 is displaced (deformed).

[0199] The second photodetector 204b amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the second photodetector circuit board 205b generates an output value as a displacement signal by converting the photocurrent output from the second photodetector 204b into a voltage.

[0200] Figure 10(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the second light-emitting element 202b to the upper surface of the light-reflecting part 207 decreases. As the biological surface 320 is displaced, the region 207b of the light-reflecting part 207 to which the second incident light 211b reaches is also displaced. Furthermore, as the region 207b of the light-reflecting part 207 is displaced, the path through which the second reflected light 212b passes also shifts upward, resulting in at least a portion of the second incident light 211b falling outside the aperture range of the fourth aperture part 1210b. As a result, the amount of light from the second reflected light 212b that reaches the second photodetector 204b decreases, and the value of the displacement signal generated by the second photodetector circuit board 205b changes. In this embodiment, when the amount of light incident on the second photodetector 204b per unit time decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower).

[0201] In this embodiment, the displacement signal output to the outside of the chestpiece 1110 may be the voltage value itself output from the first light-receiving element 204a or the second light-receiving element 204b, or it may be the signal ratio described later.

[0202] Here, we will explain the effect of setting the opening of the third aperture 1210a to be narrower than the opening of the fourth aperture 1210b, as mentioned above. As can be seen by comparing Figure 9(a) and Figure 10(a), the fourth aperture 1210b has a wider opening, so it can be said that the fourth aperture 1210b does not restrict the second reflected light 212b as much. Therefore, in the state where there is no displacement of the diaphragm 206 (Figure 10(a)), the amount of light incident on the second photodetector 204b is greater than the amount of light incident on the first photodetector 204a.

[0203] Furthermore, because the opening of the fourth aperture portion 1210b is wider than the opening of the third aperture portion 1210a, the change in the displacement signal emitted by the second light-receiving circuit board 205b when the diaphragm 206 is displaced is smaller than the change in the displacement signal emitted by the first light-receiving circuit board 205a. In other words, for example, as shown in Figure 9(b), if the first reflected light 212a does not reach the first light-receiving element 204a at all, the value of the displacement signal emitted by the first light-receiving circuit board 205a is ideally zero. On the other hand, as shown in Figure 10(b), if the amount of second reflected light 212b reaching the second light-receiving element 204b is halved, with the diaphragm 206 in a flat state as the reference, the value of the displacement signal emitted by the second light-receiving circuit board 205b is ideally about half.

[0204] Thus, in this embodiment, although the amount of light reaching the first light-receiving element 204a and the second light-receiving element 204b is arranged to change in accordance with the displacement of the biological surface 320, the rate of change of the displacement signal with respect to the amount of displacement of the biological surface 320 is different. [Relationship between the amount of displacement of the biological surface and the displacement signal according to the second embodiment]

[0205] Referring to Figure 11, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal represents the voltage output from the first light-receiving circuit board 205a and the second light-receiving circuit board 205b. The horizontal axis of Figure 11 represents the displacement d2 of the upper surface of the light-reflecting part 207 that is linked to the biological surface 320, and the vertical axis of Figure 11 represents the magnitude of the displacement signal generated by the first light-receiving circuit board 205a or the second light-receiving circuit board 205b. Graph 1500a plots the value of the displacement signal generated by the first light-receiving circuit board 205a (Sda below) for each value of displacement d2. Graph 1500b plots the value of the displacement signal generated by the second light-receiving circuit board 205b (Sdb below) for each value of displacement d2. Graph 1500c shows the displacement signal generated by the first light-receiving circuit board 205a when the output of the first light-receiving circuit board 205a is matched to the output of the second light-receiving circuit board 205b (Vmaxb) when the displacement amount d2 is zero, by increasing the light intensity of the first light-emitting element 202a.

[0206] As described above, the displacement d2 of the upper surface of the light reflecting portion 207 corresponds to the displacement of the biological surface 320, and the displacements d3a and d3b of the optical axes of the first reflected light 212a and the second reflected light 212b are proportional to d2 (Equations 1 and 4). Furthermore, as explained using Figures 9(a) and 9(b), as the first displacement d3a increases, the amount of light from the first reflected light 212a that reaches the first photodetector 204a decreases. Similarly, as the second displacement d3b increases, the amount of light from the second reflected light 212b that reaches the second photodetector 204b decreases. Here, it is assumed that the amount of light received by the first photodetector 204a decreases monotonically and linearly with respect to an increase in the first displacement d3a, and the amount of light received by the second photodetector 204b decreases monotonically and linearly with respect to an increase in the second displacement d3b. In this case, the displacement signal values ​​Sda and Sdb generated by the first light-receiving circuit board 205a and the second light-receiving circuit board 205b can be expressed by the following equations 14 and 15: Sda = Vmax a - k × d³a ... (Equation 14) Sdb = Vmax b - k × d³b ... (Equation 15)

[0207] Here, Vmaxa and Vmaxb are the values ​​of the displacement signals (Sda, Sdb) generated by the first light-receiving circuit board 205a and the second light-receiving circuit board 205b when the first displacement d3a and the second displacement d3b are zero (i.e., the displacement d2 of the biological surface 320 is zero). In other words, Vmaxa is the output of the first light-receiving circuit board 205a when the first light-receiving element 204a is receiving light of maximum intensity. Vmaxb is the output of the second light-receiving circuit board 205b when the second light-receiving element 204b is receiving light of maximum intensity. k is a proportionality constant determined by the amplification factor of the amplification circuits of the first light-receiving circuit board 205a and the second light-receiving circuit board 205b.

[0208] The first displacement d3a, which is the displacement of the optical axis of the first reflected light 212a, and the second displacement d3b, which is the displacement of the optical axis of the second reflected light 212b, can be rewritten using d2, θa, θb, φa, and φb in the same manner as in the first embodiment. That is, by substituting the aforementioned equations 1, 2, 4, and 5 into equations 14 and 15, the following equations are obtained: Sda = Vmax a - 2k × d2 × sinθa / cosφa … (Equation 16) Sdb = Vmax b - 2k × d2 × sinθb / cosφb … (Equation 17)

[0209] As shown by graphs 1500a and 1500b in Figure 11, the displacement signal values ​​Sda and Sdb decrease monotonically and linearly as the displacement amount d2 of the biological surface 320 increases. The displacement amounts d2 at which the displacement signal values ​​Sda and Sdb become zero are denoted as dmaxa and dmaxb. When the displacement amount exceeds dmaxa, the first reflected light 212a no longer reaches the first photodetector 204a, so even if the displacement amount d2 increases further, the displacement signal value Sda remains zero. Similarly, when the displacement amount exceeds dmaxb, the second reflected light 212b no longer reaches the second photodetector 204b, so even if the displacement amount d2 increases further, the displacement signal value Sdb remains zero.

[0210] In this embodiment, Vmaxa is smaller than Vmaxb. Therefore, dmaxa is smaller than dmaxb. In other words, the minimum displacement d2 at which the amount of light received by the first light-receiving element 204a becomes zero is smaller than the minimum displacement d2 at which the amount of light received by the second light-receiving element 204b becomes zero. To put it another way, using the state in which the outer surface of the diaphragm 206 is not in contact with the living body as a reference, the minimum displacement of the light-reflecting part 207 at which the first reflected light 212a no longer reaches the first light-receiving element 204a (dmaxa) is smaller than the minimum displacement of the light-reflecting part 207 at which the second reflected light 212b no longer reaches the second light-receiving element 204b (dmaxb). Therefore, the detection range of the second optical detection pair, consisting of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b, is wider than the detection range of the first optical detection pair, consisting of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a.

[0211] While Figure 11 showed Sda and Sdb as the absolute values ​​of the displacement signals, Figure 12 will be used to explain the signal ratio based on the maximum light intensity. The horizontal axis of Figure 12 represents the displacement amount d2 of the upper surface of the light reflecting part 207 that is linked to the biological surface 320, and the vertical axis of Figure 12 represents the signal ratio of the displacement signals generated by the first light receiving circuit board 205a or the second light receiving circuit board 205b. Graph 1600a plots the signal ratio for the first light receiving circuit board 205a for each value of displacement amount d2. Graph 1600b plots the signal ratio for the second light receiving circuit board 205b for each value of displacement amount d2.

[0212] The signal ratio for the first light-receiving circuit board 205a is the value obtained by dividing the displacement signal value Sda output from the first light-receiving circuit board 205a by the displacement signal value Vmaxa when the first light-receiving element 204a is receiving light of maximum intensity (Sda / Vmaxa). The signal ratio for the second light-receiving circuit board 205b is the value obtained by dividing the displacement signal value Sdb output from the second light-receiving circuit board 205b by the displacement signal value Vmaxb when the second light-receiving element 204b is receiving light of maximum intensity (Sdb / Vmaxb).

[0213] The signal ratios Sda / Vmaxa and Sdb / Vmaxb can be written as follows based on equations 16 and 17: Sda / Vmaxa = 1 - (2k × sinθa / cosφa / Vmaxa) × d² …(Equation 18) Sdb / Vmaxb = 1 - (2k × sinθb / cosφb / Vmaxb) × d² …(Equation 19)

[0214] Here, this embodiment may be configured such that, for example, θa and θb are equal and φa and φb are equal. In this case, the only difference between the right-hand side of equation 18 and the right-hand side of equation 19 is that Vmaxa and Vmaxb are different.

[0215] In this embodiment, Vmax a is smaller than Vmax b. That is, the coefficient of d2 on the right-hand side of equation 18 (-2k × sinθ a / cosφ a / Vmax a) has a larger absolute value than the coefficient of d2 on the right-hand side of equation 19 (-2k × sinθ b / cosφ b / Vmax b). In other words, the slope of graph 1600a in Figure 12 is steeper than the slope of graph 1600b.

[0216] That is, when the displacement d2 is less than or equal to dmax a, the rate of change of the amount of first reflected light 212a reaching the first photodetector 204a with respect to the displacement d2 is greater than the rate of change of the amount of second reflected light 212b reaching the second photodetector 204b with respect to the displacement d2. "Less than or equal to dmax a" means that the displacement d2 is less than or equal to the minimum value of the displacement d2 at which the first reflected light 212a no longer reaches the first photodetector 204a. Furthermore, when the displacement d2 of the light reflecting section 207 is less than or equal to dmax a, the change of the signal ratio Sda / Vmax a of the first photodetector circuit board 205a with respect to the displacement d2 is greater than the change of the signal ratio Sdb / Vmax b of the second photodetector circuit board 205b. Therefore, using the first light-emitting circuit board 203a and the first light-receiving circuit board 205a increases the sensitivity (resolution) to the displacement amount d2 that is linked to the displacement of the biological surface 320.

[0217] Thus, in this embodiment, the aperture size of the diaphragm differs between the pair of the first light-emitting circuit board 203a and the first light-receiving circuit board 205a and the pair of the second light-emitting circuit board 203b and the second light-receiving circuit board 205b. In other words, the aperture size of the diaphragm differs between the first optical detection pair and the second optical detection pair. Therefore, multiple types of vibrations can be accurately detected with a single chestpiece 110 (detection device). Furthermore, when multiple types of biological sounds are to be measured, multiple types of biological sounds can be accurately detected with a single electronic stethoscope 100.

[0218] Specifically, when detecting respiratory sounds with smaller amplitudes of biological vibration, it is preferable to use the first light-emitting element 202a and the first light-receiving element 204a, which use an optical path with a narrow aperture in the diaphragm. When detecting heart sounds with larger amplitudes of biological vibration, it is preferable to use the second light-emitting element 202b and the second light-receiving element 204b, which use an optical path with a wider aperture in the diaphragm. This allows for a wider detection range when detecting heart sounds with large amplitudes and an increased sensitivity (resolution) when detecting respiratory sounds with small amplitudes. As a result, it becomes possible to accurately detect two types of biological sounds with a single electronic stethoscope. (Modification 1)

[0219] In the state shown in Figure 9(a), if a sufficient signal-to-noise ratio (S / N ratio) cannot be obtained because the amount of light reaching the first light-receiving element 204a is insufficient, the light intensity of the first light-emitting element 202a may be increased to be greater than the light intensity of the second light-emitting element 202b. As shown in graph 1500c of Figure 11, the drive current of the first light-emitting element 202a may be increased so that the value of the displacement signal output by the first light-receiving circuit board 205a when the displacement amount d2 is zero matches the value of the displacement signal output by the second light-receiving circuit board 205b (Vmaxb). This increases the amount of light per unit area (illuminance on the light-receiving surface of the first light-receiving element 204a) of the first reflected light 212a that reaches the first light-receiving element 204a through the third aperture portion 1210a, thereby improving the S / N ratio.

[0220] When the absolute value of the displacement signal, rather than the signal ratio, is used as the output of the chestpiece 1110, it is preferable to increase the light intensity of the first light-emitting element 202a as described above. In other words, when the diaphragm 206 is flat, it is preferable that the amount of first reflected light 212a per unit area reaching the light-receiving surface of the first light-receiving element 204a is greater than the amount of second reflected light 212b per unit area reaching the light-receiving surface of the second light-receiving element 204b. When the light intensity of the first light-emitting element 202a is increased, the value Sda' of the displacement signal output by the first light-receiving circuit board 205a is represented by graph 1500c in Figure 11 and the following equation: Sda' = Vmax a - 2kc' × d2 × sinθa / cosφa … (Equation 20) kc' is a proportionality constant determined by the amplification factor of the amplification circuit of the second light-receiving circuit board 205b and the rate of change of light intensity. Comparing graphs 1500b and 1500c in Figure 11, the rate of change with respect to the displacement d2 is greater for Sda' than for Sdb. In other words, when the displacement of the biological surface 320 is the same, the displacement signal output by the first light-receiving circuit board 205a changes more significantly than the displacement signal output by the second light-receiving circuit board 205b. Therefore, similar to the second embodiment, the sensitivity (resolution) of vibration detection using the first light-emitting circuit board 203a and the first light-receiving circuit board 205a can be increased. (Modification 2)

[0221] In the second embodiment, the opening of the fourth aperture portion 1210b is wider than that of the third aperture portion 1210a, but the same effect can be obtained by making the opening of the second aperture portion 1209b wider than that of the first aperture portion 1209a. In other words, with respect to an increase in the displacement amount d2, the amount of light reaching the first photodetector 204a decreases more rapidly than the amount of light reaching the second photodetector 204b. Therefore, sensitivity can be increased by using the first light-emitting element 202a and the first photodetector 204a, and the detection range can be widened by using the second light-emitting element 202b and the second photodetector 204b. In this modified example, the opening of the first aperture portion 1209a can be called the "first opening," and the opening of the second aperture portion 1209b can be called the "second opening." Furthermore, the opening of the fourth aperture portion 1210b may be wider than that of the third aperture portion 1210a, and the opening of the second aperture portion 1209b may be wider than that of the first aperture portion 1209a. 《Third Embodiment》

[0222] Referring to Figures 19 to 21, the electronic stethoscope 100 according to the third embodiment will be described. In the third embodiment, an example will be described in which two light-emitting units and one light-receiving unit are arranged within the chestpiece 110, and two sets of optical detection pairs are formed, each sharing one light-receiving unit. [Cross-sectional configuration of the chestpiece]

[0223] The chestpiece 110 according to the third embodiment will be described with reference to Figures 19(a) and 19(b). Figure 19(a) is a cross-sectional view of the chestpiece 110 in the section shown by line A-A in Figure 19(b). Figure 19(b) is a plan view (viewed in the negative direction of the z-axis) showing the internal layout of the chestpiece 110. In Figure 19(b), the components other than the housing 208 of the chestpiece 110 are shown by viewing the housing 208 through it.

[0224] As shown in Figures 19(a) and 19(b), the chestpiece 110 includes a holding member 201, light-emitting circuit boards (203a, 203b), and a light-receiving circuit board 205. Light-emitting elements (202a, 202b) are mounted on the light-emitting circuit boards, and a light-receiving element 204 is mounted on the light-receiving circuit board 205. The chestpiece 110 also includes a diaphragm 206 with a light-reflecting portion 207 (reflecting surface) and a housing 208.

[0225] The chestpiece 110 according to this embodiment has a plurality of light-emitting units and a light-receiving unit. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit, and the light-receiving unit is shared between the two sets of displacement detection mechanisms. In other words, the chestpiece 110 has a first light-emitting circuit board 203a as a first light-emitting unit, a second light-emitting circuit board 203b as a second light-emitting unit, and a light-receiving circuit board 205 as a light-receiving unit. The other configurations are the same as in the first embodiment, so their description is omitted.

[0226] Each of the first light-emitting element 202a and the second light-emitting element 202b is a light source that emits light, and may be, for example, a light-emitting diode (LED). Power is supplied to the first light-emitting element 202a and the second light-emitting element 202b from an external power source (the battery of the gripping part 120) of the chestpiece 110.

[0227] The first light-emitting element 202a is mounted on the first light-emitting circuit board 203a, and the second light-emitting element 202b is mounted on the second light-emitting circuit board 203b. In addition to the first light-emitting element 202a, the first light-emitting circuit board 203a is mounted with peripheral circuits for defining the amount of light emitted by the first light-emitting element 202a and power terminals for receiving power from an external power source to the chestpiece 110. In addition to the second light-emitting element 202b, the second light-emitting circuit board 203b is mounted with peripheral circuits for defining the amount of light emitted by the second light-emitting element 202b and power terminals for receiving power from an external power source to the chestpiece 110. The first light-emitting circuit board 203a and the second light-emitting circuit board 203b may be printed circuit boards such as flexible circuit boards, or they may be paper phenolic substrates or glass epoxy substrates.

[0228] The first light-emitting circuit board 203a, which includes the first light-emitting element 202a, functions as a first light-emitting unit. The second light-emitting circuit board 203b, which includes the second light-emitting element 202b, functions as a second light-emitting unit.

[0229] In this embodiment, there is one first light-emitting element 202a arranged on the first light-emitting circuit board 203a, and one second light-emitting element 202b arranged on the second light-emitting circuit board 203b. However, multiple light-emitting elements (multiple first light-emitting elements 202a) may be arranged on the first light-emitting circuit board 203a, and multiple light-emitting elements (multiple second light-emitting elements 202b) may be arranged on the second light-emitting circuit board 203b. In other words, the "first light-emitting section" may include multiple light-emitting elements arranged on a single insulating substrate. Also, the "second light-emitting section" may include multiple light-emitting elements arranged on a single insulating substrate different from the insulating substrate of the first light-emitting section.

[0230] The light-receiving element 204 generates an electrical signal based on the amount of light it receives, using power supplied from a battery housed inside the gripping section 120. The power supplied to the light-receiving element 204 is supplied from the battery in the gripping section 120.

[0231] The light-receiving element 204 is mounted on the light-receiving circuit board 205. In addition to the light-receiving element 204, the light-receiving circuit board 205 is also mounted with peripheral circuits for reading signals from the light-receiving element 204. Furthermore, the light-receiving circuit board 205 is also mounted with terminals for outputting signals to the outside of the chestpiece 110 and power supply terminals for receiving power from an external power supply to the chestpiece 110.

[0232] As shown in Figure 19(a), the angle with respect to the diaphragm 206 is different for the optical path from the first light-emitting element 202a to the light-reflecting element 207 and for the optical path from the second light-emitting element 202b to the light-reflecting element 207. The angle of incidence of the light emitted by the first light-emitting element 202a (first light) to the light-reflecting element 207 is greater than the angle of incidence of the light emitted by the second light-emitting element 202b (second light) to the light-reflecting element 207.

[0233] The first light-emitting circuit board 203a and the light-receiving circuit board 205 (first optical detection pair) and the second light-emitting circuit board 203b and the light-receiving circuit board 205 (second optical detection pair) are located in the same position in the rotational direction around the center 206e of the diaphragm 206. In other words, when viewed in the direction normal to the diaphragm 206 (z-axis direction) at the center 206e of the diaphragm 206, the optical path of light from the first light-emitting unit to the light-receiving unit and the optical path of light from the second light-emitting unit to the light-receiving unit overlap. This configuration has the advantage of allowing multiple light-emitting units to be compactly arranged in the rotational direction around the center 206e of the diaphragm 206.

[0234] In this embodiment, multiple sets of optical detection pairs that share a light-receiving section are arranged, and the angle of the optical path of each optical detection pair with respect to the diaphragm 206 is different. That is, the optical path from the first light-emitting circuit board 203a to the light-receiving circuit board 205 passes at a position further away from the diaphragm 206 in the z-axis direction, except near the light-reflecting section 207, compared to the optical path from the second light-emitting circuit board 203b to the light-receiving circuit board 205. This makes it possible to avoid a decrease in detection accuracy due to light interference between optical detection pairs (light emitted from the light-emitting section of one optical detection pair entering the light-receiving section of the other optical detection pair).

[0235] Furthermore, for example, the light emitted from the first light-emitting circuit board 203a and the light emitted from the second light-emitting circuit board 203b are both reflected near the center 206e of the diaphragm 206. In other words, within the light-reflecting portion 207, the area where light from the first light-emitting element 202a is irradiated when the diaphragm 206 is not being pressed by a living organism (first effective range) is defined as region 207a. Similarly, the area where light from the second light-emitting element 202b is irradiated when the diaphragm 206 is not being pressed by a living organism (second effective range) is defined as region 207b. In this case, both region 207a (first effective range) and region 207b (second effective range) overlap with the center 206e of the diaphragm 206 when viewed in the z-axis direction. As a result, for each of the first and second optical detection pairs, the displacement of the biological surface 320 can be detected using the central part where the displacement of the diaphragm 206 is greatest, thereby improving the accuracy of biological sound detection.

[0236] In the example shown in Figures 19(a) and 19(b), the portion of the holding member 201 through which the first incident light 211a passes corresponds to the first aperture portion 209a. The portion of the holding member 201 through which the second incident light 211b passes corresponds to the second aperture portion 209b.

[0237] The light-receiving element 204 is positioned to receive the first reflected light 212a and the second reflected light 212b. Specifically, the light-receiving element 204 is positioned so that the amount of first reflected light 212a received changes due to the vibration of the diaphragm 206 in the z-axis direction. In addition, the light-receiving element 204 is positioned so that the amount of second reflected light 212b received changes due to the vibration of the diaphragm 206 in the z-axis direction.

[0238] The chestpiece 110 has a third aperture section 210a and a fourth aperture section 210b that narrow the light specularly reflected by the light reflecting section 207. The third aperture section 210a suppresses diffusely reflected light from entering the photodetector 204, allowing only specularly reflected light from the light reflecting section 207 (first reflected light 212a) to reach the photodetector 204. The fourth aperture section 210b suppresses diffusely reflected light from entering the photodetector 204, allowing only specularly reflected light from the light reflecting section 207 (second reflected light 212b) to reach the photodetector 204. Furthermore, the third aperture section 210a and the fourth aperture section 210b further narrow the specularly reflected light from the light reflecting section 207, allowing only a portion of the specularly reflected light to reach the photodetector 204.

[0239] The third aperture portion 210a functions as a first aperture that narrows the optical path from the light-reflecting portion 207 to the light-receiving element 204 so that the area of ​​the portion of the light-receiving surface of the light-receiving element 204 that receives the first reflected light 212a changes according to the amount of displacement of the light-reflecting portion 207. The fourth aperture portion 210b functions as a second aperture that narrows the optical path from the light-reflecting portion 207 to the light-receiving element 204 so that the area of ​​the portion of the light-receiving surface of the light-receiving element 204 that receives the second reflected light 212b changes according to the amount of displacement of the light-reflecting portion 207.

[0240] In the example shown in Figures 19(a) and 19(b), the portion of the holding member 201 through which the first reflected light 212a passes corresponds to the third diaphragm 210a (first opening). The portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth diaphragm 210b (second opening). [Example of operation of the electronic stethoscope according to the third embodiment]

[0241] Referring to Figures 20(a) and 20(b), a basic example of the operation of the chestpiece 110 of the electronic stethoscope 100 will be described.

[0242] As shown in Figures 20(a) and 20(b), the chestpiece 110 is used in contact with the biological surface 320 of the subject. Therefore, the biological surface 320, the diaphragm 206, and the light-reflecting part 207 vibrate together. The vibration or displacement of the biological surface 320 occurs in response to bodily movements such as heartbeat and respiration of the person having the biological surface 320. The chestpiece 110 detects the displacement of the upper surface of the light-reflecting part 207 in the z-axis direction. The electronic auscultation device 100 can acquire vibration data of the biological surface 320, including body temperature, by optically detecting the displacement of the light-reflecting part 207 using the chestpiece 110.

[0243] Figure 20(a) shows a cross-sectional view of the chestpiece 110 when the diaphragm 206 is flat. The first aperture portion 209a and the third aperture portion 210a are arranged so that, when the diaphragm 206 is flat, more first reflected light 212a is received by the photodetector 204 compared to when the diaphragm 206 is displaced (deformed). Similarly, the second aperture portion 209b and the fourth aperture portion 210b are arranged so that, when the diaphragm 206 is flat, more second reflected light 212b is received by the photodetector 204 compared to when the diaphragm 206 is displaced (deformed). The state in which the diaphragm 206 is flat is a state in which the amount of displacement of the center 206e of the diaphragm 206 in the z-axis direction is 0, and the state in which the diaphragm 206 is deformed (displaced) is a state in which the amount of displacement of the center 206e in the z-axis direction is not 0.

[0244] The first aperture section 209a and the third aperture section 210a form an optical path through which light emitted from the first light-emitting element 202a is directed toward the photodetector 204 via the light-reflecting section 207. The second aperture section 209b and the fourth aperture section 210b form an optical path through which light emitted from the second light-emitting element 202b is directed toward the photodetector 204 via the light-reflecting section 207. In other words, the first aperture section 209a and the third aperture section 210a can be called optical path forming sections that form an optical path relating to the first light-emitting element 202a and the photodetector 204. The second aperture section 209b and the fourth aperture section 210b can also be called optical path forming sections that form an optical path relating to the second light-emitting element 202b and the photodetector 204. Furthermore, the first aperture section 209a is an example of a first optical path forming section that forms a first optical path from the light-emitting element 202 toward the first region of the light-reflecting section 207 (reflective surface). The second aperture portion 209b is an example of a second optical path forming portion that forms a second optical path from the light-emitting element 202 toward the second region of the light-reflecting portion 207 (reflecting surface).

[0245] The light-receiving element 204 amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the light-receiving circuit board 205 converts the photocurrent output from the light-receiving element 204 into a voltage, generates an output value as a displacement signal, and outputs it to the outside of the chestpiece 110. In this embodiment, the displacement signal refers to the output value of the light-receiving circuit board 205 that reflects the state and deformation of the diaphragm 206 at any given time.

[0246] Figure 20(b) shows a cross-sectional view of the chestpiece 110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the first light-emitting element 202a to the upper surface of the light-reflecting part 207 decreases. As the biological surface 320 is displaced, the region 207a of the light-reflecting part 207 to which the first incident light 211a reaches is also displaced. Furthermore, as the region 207a of the light-reflecting part 207 is displaced, the path through which the first reflected light 212a passes also shifts upward, resulting in at least a portion of the first reflected light 212a falling outside the aperture range of the third aperture part 210a. As a result, the amount of light from the first reflected light 212a that reaches the photodetector 204 decreases, and the value of the displacement signal generated by the photodetector circuit board 205 changes. In this embodiment, when the amount of light per unit time incident on the photodetector 204 decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower). As shown in Figure 20(b), if the first reflected light 212a does not reach the photodetector 204 at all, the value of the displacement signal will ideally be zero.

[0247] Similarly, as shown in Figure 20(b), when the biological surface 320 is displaced, the region 207b of the light-reflecting portion 207 to which the second incident light 211b reaches is also displaced. Furthermore, as the region 207b of the light-reflecting portion 207 is displaced, the path through which the second reflected light 212b passes also shifts upward, resulting in at least a portion of the second reflected light 212b falling outside the aperture range of the fourth aperture portion 210b. As a result, the amount of light from the second reflected light 212b that reaches the photodetector 204 decreases, and the value of the displacement signal generated by the photodetector circuit board 205 changes. In this embodiment, when the amount of light per unit time incident on the photodetector 204 decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower). As shown in Figure 20(b), when about half of the second reflected light 212b reaches the photodetector 204, the value of the displacement signal is ideally halved, based on the case where the diaphragm 206 is flat. [Hardware configuration of the electronic stethoscope]

[0248] Figure 28 shows an example of the hardware configuration of the electronic stethoscope 100. The hardware configuration shown in Figure 28 differs from that in Figure 18 in that it has one light-receiving circuit board, but the other configurations are the same as in Figure 18.

[0249] In this embodiment, for example, when the respiratory sound mode is selected, only the first light-emitting circuit board 203a (first light-emitting part) of the first light-emitting circuit board 203a (first light-emitting part) and the second light-emitting circuit board 203b (second light-emitting part) are driven in the chestpiece 110. That is, the first light-emitting element 202a emits light while the second light-emitting element 202b is turned off. In this case, the chestpiece 110 outputs a displacement signal to the sound output unit 510 corresponding to the amount of first reflected light 212a that has reached the light-receiving element 204. On the other hand, for example, when the heart sound mode is selected, only the second light-emitting circuit board 203b (second light-emitting part) of the second light-emitting circuit board 203b (second light-emitting part) are driven in the chestpiece 110. That is, the second light-emitting element 202b emits light while the second light-emitting element 202b is turned off. In this case, the chestpiece 110 outputs a displacement signal to the sound output unit 510 corresponding to the amount of second reflected light 212b that reaches the light-receiving element 204. [Relationship between diaphragm displacement and reflected light axis displacement]

[0250] Here, with reference to Figures 21(a) and 21(b), the relationship between the displacement of the biological surface 320 and the displacement of the optical axis position of the reflected light on the light-receiving surface of the light-receiving element 204 will be explained. Figure 21(a) is a schematic diagram showing the positional relationship between the first light-emitting element 202a, the upper surface of the light-reflecting part 207, and the light-receiving element 204. Figure 21(b) is a schematic diagram showing the positional relationship between the second light-emitting element 202b and the upper surface of the light-reflecting part 207.

[0251] In Figure 21(a), position 401 indicates the reference position of the upper surface of the light-reflecting portion 207 in the z-axis direction. In this embodiment, the reference position is the position of the upper surface of the aforementioned region 207a of the light-reflecting portion 207 when the diaphragm 206 is flat. Position 402 indicates the position where the upper surface of the light-reflecting portion 207 is displaced upward by a certain displacement amount d2 from position 401. Since the displacement amount d2 of the light-reflecting portion 207 is small compared to the diameter of the diaphragm 206, even when the upper surface of the light-reflecting portion 207 is at position 402, the region 207a of the upper surface of the light-reflecting portion 207 is assumed to be flat. Furthermore, in the following description, the displacement amount d2 is assumed to be a non-negative value regardless of whether the direction of displacement is in the positive or negative direction of the z-axis.

[0252] In Figure 21(a), the first incident optical axis 403a represents the optical axis of the first incident light 211a. The angle of incidence of the first incident optical axis 403a with respect to the light reflecting section 207 is denoted as the first angle of incidence, and is represented by θa. The first angle of incidence θa is defined by the angle between the first incident optical axis 403a and the normal to the upper surface of the light reflecting section 207. The optical axis of the first reflected light 212a when the upper surface of the light reflecting section 207 is at position 401 is defined as the first reflected optical axis 404a. The optical axis of the first reflected light 212a when the upper surface of the light reflecting section 207 is at position 402 is defined as the second reflected optical axis 405a. Since the first incident light 211a is specularly reflected at the upper surface of the light reflecting section 207, the first angle of reflection of the first reflected light 212a is also θa. The first reflected optical axis 404a and the second reflected optical axis 405a are parallel to each other. Furthermore, let φa be the angle of incidence of the first reflected light 212a to the light-receiving element 204. φa may be a value other than 0°.

[0253] The first displacement amount d3a is defined as the amount of displacement of the optical axis of the first reflected light 212a on the light-receiving surface of the light-receiving element 204 when the upper surface of the light-reflecting part 207 is displaced from position 401 (reference position) to position 402. The first displacement amount d3a can also be expressed as the distance from the position where the first reflected optical axis 404a intersects the light-receiving surface of the light-receiving element 204 to the position where the second reflected optical axis 405a intersects the light-receiving surface of the light-receiving element 204.

[0254] The ratio of the first displacement d3a to the displacement d2 is expressed as the first displacement ratio Ga. In this case, the following relationships, Equations 21 and 22, hold: d3a = Ga × d2 …(Equation 21) Ga = 2 × sinθa / cosφa …(Equation 22)

[0255] From equation 22, it can be seen that even if the displacement d2 of the light reflecting part 207 is the same, the larger the incident angle θa, the larger the first displacement magnification Ga becomes, and the larger the incident angle φa, the larger the first displacement magnification Ga becomes. In other words, the larger the first incident angle θa, the larger the first displacement d3a becomes. Note that when the incident angle φa is 0°, that is, when the first reflected optical axis 404a and the second reflected optical axis 405a are perpendicular to the light-receiving surface of the light-receiving element 204, equation 22 can be rewritten as follows: Ga = 2 × sinθa … (Equation 23)

[0256] In Figure 21(b), the second incident optical axis 403b represents the optical axis of the second incident light 211b. The angle of incidence of the second incident optical axis 403b with respect to the light reflecting section 207 is defined as the second incident angle, and is represented by θb. The second incident angle θb is defined by the angle between the second incident optical axis 403b and the normal to the upper surface of the light reflecting section 207. The optical axis of the second reflected light 212b when the upper surface of the light reflecting section 207 is at position 401 is defined as the third reflected optical axis 404b. The optical axis of the second reflected light 212b when the upper surface of the light reflecting section 207 is at position 402 is defined as the fourth reflected optical axis 405b. Since the second incident light 211b is specularly reflected at the upper surface of the light reflecting section 207, the second reflection angle of the second reflected light 212b is also θb. The third reflected optical axis 404b and the fourth reflected optical axis 405b are parallel to each other. Furthermore, let φb be the angle of incidence of the second reflected light 212b to the photodetector 204. φb may be a value other than 0°.

[0257] The second displacement amount d3b is the amount of displacement of the optical axis of the second reflected light 212b on the light-receiving surface of the light-receiving element 204 when the upper surface of the light-reflecting part 207 is displaced from position 401 (reference position) to position 402. The second displacement amount d3b can also be expressed as the distance from the position where the third reflected optical axis 404b intersects the light-receiving surface of the light-receiving element 204 to the position where the fourth reflected optical axis 405b intersects the light-receiving surface of the light-receiving element 204.

[0258] The ratio of the second displacement d3b to the displacement d2 is expressed as the second displacement ratio Gb. In this case, the following relationships, Equations 24 and 25, hold: d3b = Gb × d2 …(Equation 24) Gb = 2 × sinθb / cosφb …(Equation 25)

[0259] From equation 25, it can be seen that even if the displacement d2 of the light reflecting part 207 is the same, the larger the incident angle θb, the larger the second displacement magnification Gb, and the larger the incident angle φb, the larger the second displacement magnification Gb. In other words, the larger the second incident angle θb, the larger the second displacement d3b. Note that when the incident angle φb is 0°, that is, when the third reflected optical axis 404b and the fourth reflected optical axis 405b are perpendicular to the light-receiving surface of the light-receiving element 204, equation 25 can be rewritten as follows: Gb = 2 × sinθb … (Equation 26)

[0260] As can be seen from equations 21 to 26, the larger the incident angle (θa, θb) of the incident optical axis with respect to the light reflecting part 207, the larger the displacement (d3a, d3b) of the reflected optical axis at the light receiving surface of the light receiving part.

[0261] In this embodiment, the first incident angle θa is set to be greater than the second incident angle θb. Also, in this embodiment, the incident angles φa and φb of the reflected light to the light-receiving element 204 are set to be equal. The following relationship holds between the first displacement magnification Ga and the second displacement magnification Gb: Ga > Gb ... (Equation 27)

[0262] In other words, if the displacement of the biological surface 320 is the same, the displacement of the reflected light axis of the first reflected light 212a (d3a) at the light-receiving surface of the light-receiving element 204 will be greater than the displacement of the reflected light axis of the second reflected light 212b (d3b).

[0263] In this embodiment, the displacement ratios (Ga, Gb) differ between the first light-emitting circuit board 203a and the second light-emitting circuit board 203b. In other words, the displacement ratios differ between the first optical detection pair and the second optical detection pair. Therefore, when measuring multiple types of biological sounds, an appropriate displacement ratio can be set for each optical detection pair according to the amplitude of the biological sound, enabling accurate detection of multiple types of biological sounds with a single electronic stethoscope.

[0264] Specifically, when detecting respiratory sounds with smaller amplitudes of biological vibration, it is preferable to use the first light-emitting element 202a, which has a large angle of incidence to the light-reflecting section 207, for detection. In this case, the second light-emitting element 202b may be turned off. When detecting heart sounds with larger amplitudes of biological vibration, it is preferable to use the second light-emitting element 202b, which has a small angle of incidence to the light-reflecting section 207, for detection. In this case, the first light-emitting element 202a may be turned off. By switching between the first light-emitting element 202a and the second light-emitting element 202b in this way, the detection range can be widened when detecting heart sounds with large amplitudes, and the sensitivity (resolution) can be increased when detecting respiratory sounds with small amplitudes. As a result, it becomes possible to accurately detect two types of biological sounds with a single electronic stethoscope. [Relationship between displacement of the biological surface and displacement signal]

[0265] Referring to Figure 22, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal represents the voltage output from the light-receiving circuit board 205. The horizontal axis of Figure 22 represents the displacement d2 of the upper surface of the light-reflecting part 207 that is linked to the biological surface 320 (see also Figures 21(a) and (b)), and the vertical axis of Figure 22 represents the magnitude of the displacement signal generated by the light-receiving circuit board 205. Graph 500a plots the value of the displacement signal (Sda below) generated by the light-receiving circuit board 205 in response to the light emitted by the first light-emitting element 202a for each displacement d2. Graph 500b plots the value of the displacement signal (Sdb below) generated by the light-receiving circuit board 205 in response to the light emitted by the second light-emitting element 202b for each displacement d2.

[0266] According to the electronic stethoscope 100 of this embodiment, by arranging multiple light-emitting units with different incident angles (θa, θb) to the light-reflecting unit 207, appropriate displacement ratios Ga and Gb can be set for multiple types of biological sounds. Therefore, multiple types of vibrations can be accurately detected with a single chestpiece 110 (detection device). Furthermore, multiple types of biological sounds can be accurately detected with a single electronic stethoscope. 《Fourth Embodiment》

[0267] Referring to Figures 22(a) to 27, the chestpiece 1110 of the electronic stethoscope 100 according to the fourth embodiment will be described. Hereinafter, elements with reference numerals common to the first to third embodiments will have basically the same configuration and function unless otherwise specified, and the parts that differ from the first to third embodiments will be mainly described.

[0268] First, the configuration of the chestpiece 1110 will be explained using Figures 22(a) and 22(b), and Figures 23(a) and 23(b). Figure 22(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line C-C in Figure 22(b). Figure 22(b) is a plan view (viewed in the negative z-axis direction) showing the internal layout of the chestpiece 1110. Figure 23(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line D-D in Figure 23(b). Figure 23(b) is a plan view showing the internal layout of the chestpiece 1110. Note that in Figures 22(b) and 23(b), the components other than the housing 208 of the chestpiece 1110 are shown by viewing the housing 208 through the housing 208.

[0269] As shown in Figures 22(a) to 23(b), the chestpiece 1110 includes a holding member 1201, light-emitting circuit boards (203a, 203b) including light-emitting elements (202a, 202b), and a light-receiving circuit board 205 including a light-receiving element 204. The chestpiece 1110 also includes a diaphragm 206 including a light-reflecting portion 207 and a housing 208.

[0270] The chestpiece 1110 according to this embodiment has a plurality of light-emitting units and a light-receiving unit. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit, and the light-receiving unit is shared between the two sets of displacement detection mechanisms. In other words, the chestpiece 1110 has a first light-emitting circuit board 203a as a first light-emitting unit, a second light-emitting circuit board 203b as a second light-emitting unit, and a light-receiving circuit board 205 as a light-receiving unit.

[0271] The housing 208 houses the holding member 1201, the light-emitting circuit boards (203a, 203b), and the light-receiving circuit board 205. Since the holding member 1201 has aperture sections (1209a, 1209b, 1210a, 1210b), the housing 208 can house the aperture sections. Note that the components of the chestpiece 1110 described here are just examples, and in addition to the components described above, the chestpiece 1110 may also have a circuit board on which circuit elements for controlling the operation of the chestpiece 1110 are mounted.

[0272] The first light-emitting circuit board 203a, which includes the first light-emitting element 202a, functions as a first light-emitting unit. The second light-emitting circuit board 203b, which includes the second light-emitting element 202b, functions as a second light-emitting unit. The light-receiving circuit board 205, which includes the light-receiving element 204, functions as a light-receiving unit.

[0273] As can be seen from Figures 22(b) and 23(b), when viewed in the z-axis direction, the optical path from the first light-emitting element 202a to the photodetector 204 and the optical path from the second light-emitting element 202b to the photodetector 204 do not overlap except in the vicinity of the photodetector 204. In particular, the optical path from the first light-emitting element 202a to the light-reflecting part 207 and the optical path from the second light-emitting element 202b to the light-reflecting part 207 do not overlap when viewed in the z-axis direction. Also, when viewed in the z-axis direction, the first light-emitting circuit board 203a and the second light-emitting circuit board 203b do not overlap. The first light-emitting circuit board 203a and the second light-emitting circuit board 203b are positioned apart from each other in the rotational direction around an axis that passes through the center 206e of the diaphragm 206 and extends in a direction perpendicular to the contact surface 206a of the diaphragm 206. This configuration makes it possible to avoid a decrease in detection accuracy due to light interference. In other words, when detecting vibrations of the biological surface 320 using either the first light-emitting element 202a or the second light-emitting element 202b, the possibility of stray light reaching the photodetector 204 through the optical path corresponding to the other light-emitting element can be reduced.

[0274] In the examples of Figures 22(a)(b) and 23(a)(b), the portion of the holding member 1201 through which the first incident light 211a passes corresponds to the first aperture portion 1209a.

[0275] In the examples of Figures 22(a)(b) and 23(a)(b), the portion of the holding member 1201 through which the first incident light 211a passes corresponds to the first aperture portion 1209a (first opening). The portion of the holding member 201 through which the second incident light 211b passes corresponds to the second aperture portion 1209b (second opening). The portion of the holding member 1201 through which the first reflected light 212a passes corresponds to the third aperture portion 1210a (third opening). Furthermore, the portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth aperture portion 1210b (fourth opening).

[0276] As shown in Figures 22(a) and 23(a), in this embodiment, the opening of the first aperture 1209a (first opening) is set to be narrower than the opening of the second aperture 1209b (second opening). In other words, the opening area of ​​the first aperture 1209a when viewed in the direction from the light reflecting portion 207 toward the first light-emitting element 202a is smaller than the opening area of ​​the second aperture 1209b when viewed in the direction from the light reflecting portion 207 toward the second light-emitting element 202b. Therefore, the area of ​​the region on the upper surface of the light reflecting portion 207 that is irradiated with light from the first light-emitting element 202a is smaller than the area of ​​the region that is irradiated with light from the second light-emitting element 202b. Also, the area over which the light-receiving element 204 receives reflected light from the light reflecting portion 207 is smaller than the area over which the light-receiving element 204 receives reflected light from the light reflecting portion 207. [Example of operation of the electronic stethoscope according to the fourth embodiment]

[0277] An example of the operation of the chestpiece 1110 according to the fourth embodiment will be described with reference to Figures 24(a) and 24(b), and Figures 25(a) and 25(b). Figures 24(a) and 24(b) show an example of the operation of the first light-emitting circuit board 203a and the light-receiving circuit board 205. Figures 25(a) and 25(b) show an example of the operation of the second light-emitting circuit board 203b and the light-receiving circuit board 205.

[0278] Figure 24(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The first aperture portion 1209a and the third aperture portion 1210a are arranged so that when the diaphragm 206 is flat, more of the first reflected light 212a is received by the light-receiving element 204 compared to when the diaphragm 206 is displaced (deformed).

[0279] Figure 24(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the first light-emitting element 202a to the upper surface of the light-reflecting part 207 decreases. As the biological surface 320 is displaced, the region 207a of the light-reflecting part 207 to which the first incident light 211a reaches is also displaced. Furthermore, as the region 207a of the light-reflecting part 207 is displaced, the path through which the first reflected light 212a passes also shifts upward, resulting in at least a portion of the first reflected light 212a falling outside the aperture range of the third aperture part 1210a. As a result, the amount of light from the first reflected light 212a that reaches the photodetector 204 decreases, and the value of the displacement signal generated by the photodetector circuit board 205 changes. In this embodiment, when the amount of light per unit time incident on the photodetector 204 decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower).

[0280] Figure 25(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The second aperture portion 1209b and the fourth aperture portion 1210b are arranged so that when the diaphragm 206 is flat, more second reflected light 212b is received by the light-receiving element 204 compared to when the diaphragm 206 is displaced (deformed).

[0281] Figure 25(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the second light-emitting element 202b to the upper surface of the light-reflecting portion 207 decreases. As the biological surface 320 is displaced, the region 207b of the light-reflecting portion 207 to which the second incident light 211b reaches is also displaced. Furthermore, as the region 207b of the light-reflecting portion 207 is displaced, the path through which the second reflected light 212b passes also shifts upward, resulting in at least a portion of the second incident light 211b falling outside the aperture range of the fourth aperture portion 1210b. As a result, the amount of light from the second reflected light 212b that reaches the photodetector 204 decreases, and the value of the displacement signal generated by the photodetector circuit board 205 changes.

[0282] The opening of the first aperture portion 1209a is set to be narrower than the opening of the second aperture portion 1209b. Also, the opening of the second aperture portion 1209b is wider than the opening of the first aperture portion 1209a. Therefore, when the diaphragm 206 is displaced, the rate of change of the amount of second reflected light 212b incident on the photodetector 204 is smaller than the rate of change of the amount of first reflected light 212a incident on the photodetector 204.

[0283] Thus, in this embodiment, although the amount of light reaching the light-receiving element 204 changes according to the displacement of the biological surface 320, the rate of change of the displacement signal with respect to the amount of displacement of the biological surface 320 differs when the first light-emitting element 202a is used and when the second light-emitting element 202b is used. [Relationship between the amount of displacement of the biological surface and the displacement signal according to the fourth embodiment]

[0284] Referring to Figure 26, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal represents the voltage output from the light-receiving circuit board 205. The horizontal axis of Figure 26 represents the displacement d2 of the upper surface of the light-reflecting part 207 that is linked to the biological surface 320, and the vertical axis of Figure 26 represents the magnitude of the displacement signal generated by the light-receiving circuit board 205. Graph 1500a plots the value of the displacement signal (Sda below) generated by the light-receiving circuit board 205 in response to the light emitted by the first light-emitting element 202a for each value of displacement d2. Graph 1500b plots the value of the displacement signal (Sdb below) generated by the light-receiving circuit board 205 in response to the light emitted by the second light-emitting element 202a for each value of displacement d2. Graph 1500c shows the displacement signal generated by the light-receiving circuit board 205 when the light intensity of the first light-emitting element 202a is increased, thereby matching the output of the light-receiving circuit board 205 to the same value (Vmaxb) as when the displacement amount d2 is zero, as when the second light-emitting element 202b is used.

[0285] Thus, in this embodiment, the aperture size of the diaphragm differs between the set of the first light-emitting circuit board 203a and the light-receiving circuit board 205 and the set of the second light-emitting circuit board 203b and the light-receiving circuit board 205. In other words, the aperture size of the diaphragm differs between the first optical detection pair and the second optical detection pair. Therefore, multiple types of vibrations can be accurately detected with a single chestpiece 110 (detection device). Furthermore, when multiple types of biological sounds are to be measured, multiple types of biological sounds can be accurately detected with a single electronic stethoscope.

[0286] Specifically, when detecting respiratory sounds with smaller amplitudes of biological vibrations, it is preferable to use the first light-emitting element 202a and the light-receiving element 204, which use an optical path with a narrow aperture in the diaphragm. When detecting heart sounds with larger amplitudes of biological vibrations, it is preferable to use the second light-emitting element 202b, which uses an optical path with a wider aperture in the diaphragm. This allows for a wider detection range when detecting heart sounds with large amplitudes and an increased sensitivity (resolution) when detecting respiratory sounds with small amplitudes. As a result, it becomes possible to accurately detect two types of biological sounds with a single electronic stethoscope. 《Fifth Embodiment》

[0287] Next, the electronic stethoscope 100 according to the fifth embodiment will be described. [Cross-sectional configuration of the chestpiece]

[0288] The chestpiece 110 according to the fifth embodiment will be described with reference to Figures 29(a) and 29(b). Figure 29(a) is a cross-sectional view of the chestpiece 110 in the section shown by line A-A in Figure 29(b). Figure 29(b) is a plan view (viewed in the negative z-axis direction) showing the internal layout of the chestpiece 110.

[0289] The chestpiece 110 according to this embodiment has one light-emitting unit and a plurality of light-receiving units. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit, and the light-emitting unit is shared between the two sets of displacement detection mechanisms. In other words, the chestpiece 110 has a light-emitting circuit board 203 as a light-emitting unit, a first light-receiving circuit board 205a as a first light-receiving unit, and a second light-receiving circuit board 205b as a second light-receiving unit.

[0290] Hereinafter, a set consisting of one light-emitting unit (light-emitting circuit board) and one corresponding light-receiving unit (light-receiving circuit board) may be referred to as an optical detection pair. In this embodiment, one light-emitting unit and two light-receiving units are arranged within the chestpiece 110, forming two sets of optical detection pairs that share one light-emitting unit. The other configurations are the same as in the first embodiment, so their explanation will be omitted.

[0291] In this embodiment, there is one light-emitting element 202 arranged on the light-emitting circuit board 203. However, multiple light-emitting elements 202 may be arranged on the light-emitting circuit board 203. In other words, the "light-emitting section" may include multiple light-emitting elements arranged on a single insulating substrate.

[0292] In this embodiment, there is one first light-receiving element 204a on the first light-receiving circuit board 205a, and one second light-receiving element 204b on the second light-receiving circuit board 205b. However, multiple light-receiving elements (multiple first light-receiving elements 204a) may be arranged on the first light-receiving circuit board 205a, and multiple light-receiving elements (multiple second light-receiving elements 204b) may be arranged on the second light-receiving circuit board 205b. In other words, the "first light-receiving unit" may include multiple light-receiving elements arranged on a single insulating substrate. Also, the "second light-receiving unit" may include multiple light-receiving elements arranged on a single insulating substrate separate from the insulating substrate of the first light-receiving unit.

[0293] As shown in Figure 29(a), the angle with respect to the diaphragm 206 is different for the optical path from the light-emitting element 202 through the light-reflecting section 207 to the first light-receiving element 204a and for the optical path from the light-emitting element 202 through the light-reflecting section 207 to the second light-receiving element 204b. The angle of incidence of the light that ultimately goes to the first light-receiving element 204a (first light) with respect to the light-reflecting section 207 is greater than the angle of incidence of the light that ultimately goes to the second light-receiving element 204b but is emitted (second light) with respect to the light-reflecting section 207.

[0294] The pair of light-emitting circuit board 203 and first light-receiving circuit board 205a (first optical detection pair) and the pair of light-emitting circuit board 203 and second light-receiving circuit board 205b (second optical detection pair) are located in the same position in the rotational direction around the center 206e of the diaphragm 206. In other words, when viewed in the direction normal to the diaphragm 206 (z-axis direction) at the center 206e of the diaphragm 206, the optical path of light from the light-emitting unit toward the first light-receiving unit and the optical path of light from the light-emitting unit toward the second light-receiving unit overlap. This configuration has the advantage of allowing multiple light-emitting units to be compactly arranged in the rotational direction around the center 206e of the diaphragm 206.

[0295] In this embodiment, multiple pairs of optical detection devices that share a light-emitting section are arranged, and the angle of the optical path of each optical detection pair with respect to the diaphragm 206 is different. That is, the optical path from the light-emitting circuit board 203 to the first light-receiving circuit board 205a passes at a position further away from the diaphragm 206 in the z-axis direction, except near the light-reflecting section 207, compared to the optical path from the light-emitting circuit board 203 to the second light-receiving circuit board 205b. This makes it possible to avoid a decrease in detection accuracy due to light interference between optical detection pairs.

[0296] Furthermore, for example, the light that ultimately heads toward the first light-receiving circuit board 205a and the light that ultimately heads toward the second light-receiving circuit board 205b are both reflected near the center 206e of the diaphragm 206. In other words, of the light-reflecting portion 207, the range of the light-reflecting portion 207 that reflects light toward the first light-receiving circuit board 205a when the diaphragm 206 is not pressed by a living organism (first effective range) is defined as region 207a. The range of the light-reflecting portion 207 that reflects light toward the second light-receiving circuit board 205b when the diaphragm 206 is not pressed by a living organism (second effective range) is defined as region 207b. In this case, both region 207a (first effective range) and region 207b (second effective range) overlap with a virtual straight line (line A-A in Figure 29) passing through the center 206e of the diaphragm 206 when viewed in the z-axis direction. As a result, for each of the first and second optical detection pairs, the displacement of the biological surface 320 can be detected using the central area where the displacement of the diaphragm 206 is greatest, thereby improving the accuracy of biological sound detection.

[0297] In the example shown in Figures 29(a) and 29(b), the portion of the holding member 201 through which the first incident light 211a passes corresponds to the first aperture portion 209a (opening). The portion of the holding member 201 through which the second incident light 211b passes corresponds to the second aperture portion 209b (opening).

[0298] The first light-receiving element 204a and the second light-receiving element 204b are arranged to receive the first reflected light 212a and the second reflected light 212b, respectively. Specifically, the first light-receiving element 204a is positioned so that the amount of first reflected light 212a received changes due to the vibration of the diaphragm 206 in the z-axis direction. The second light-receiving element 204b is positioned so that the amount of second reflected light 212b received changes due to the vibration of the diaphragm 206 in the z-axis direction.

[0299] The first light-receiving element 204a and the second light-receiving element 204b are positioned so that more light is incident on the diaphragm 206 when it is not in contact with the biological surface (i.e., when the diaphragm 206 is flat) compared to when the diaphragm 206 is vibrating. In other words, the first light-receiving element 204a and the second light-receiving element 204b output electrical signals corresponding to the amount of first reflected light 212a and second reflected light 212b they receive, and the amount of displacement of the diaphragm 206 can be determined based on these electrical signals. This principle will be described later.

[0300] Furthermore, the chestpiece 110 has a third aperture section 210a and a fourth aperture section 210b that narrow the light specularly reflected by the light reflecting section 207. The third aperture section 210a suppresses diffusely reflected light from entering the first light-receiving element 204a, allowing only specularly reflected light from the light reflecting section 207 to reach the first light-receiving element 204a. The fourth aperture section 210b suppresses diffusely reflected light from entering the second light-receiving element 204b, allowing only specularly reflected light from the light reflecting section 207 to reach the second light-receiving element 204b. In addition, the third aperture section 210a and the fourth aperture section 210b further narrow the specularly reflected light from the light reflecting section 207, allowing only a portion of the specularly reflected light to reach the first light-receiving element 204a and the second light-receiving element 204b.

[0301] The third aperture portion 210a functions as a first aperture that narrows the optical path from the light-reflecting portion 207 to the first light-receiving element 204a so that the area of ​​the portion of the light-receiving surface of the first light-receiving element 204a that receives light changes according to the amount of displacement of the light-reflecting portion 207. The fourth aperture portion 210b functions as a second aperture that narrows the optical path from the light-reflecting portion 207 to the second light-receiving element 204b so that the area of ​​the portion of the light-receiving surface of the second light-receiving element 204b that receives light changes according to the amount of displacement of the light-reflecting portion 207.

[0302] In the example shown in Figures 29(a) and 29(b), the portion of the holding member 201 through which the first reflected light 212a passes corresponds to the third diaphragm portion 210a (opening). Furthermore, the portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth diaphragm portion 210b (opening). [Hardware configuration of the electronic stethoscope]

[0303] Refer to Figure 37 for an example of the hardware configuration of the electronic stethoscope 100. The hardware configuration in Figure 37 differs from that in Figure 18 only in that the light-emitting circuit board has been changed to one; all other configurations are the same as in Figure 18.

[0304] In this embodiment, for example, when the respiratory sound mode is selected, only the light-emitting circuit board 203 (light-emitting part) and the first light-receiving circuit board 205a (first light-receiving part) are driven in the chestpiece 110. That is, the light-emitting element 202 emits light, and a displacement signal corresponding to the photocurrent output by the first light-receiving element 204a is output to the sound output unit 510, while the amount of light received by the second light-receiving element 204b is not reflected in the displacement signal. On the other hand, for example, when the heart sound mode is selected, only the light-emitting circuit board 203 (light-emitting part) and the second light-receiving circuit board 205b (second light-receiving part) are driven in the chestpiece 110. That is, the light-emitting element 202 emits light, and a displacement signal corresponding to the photocurrent output by the second light-receiving element 204b is output to the sound output unit 510, while the amount of light received by the first light-receiving element 204a is not reflected in the displacement signal. [Relationship between diaphragm displacement and reflected light axis displacement]

[0305] Here, with reference to Figure 31, the relationship between the displacement of the biological surface 320 and the displacement of the optical axis position of the reflected light on the light-receiving surfaces of the first light-receiving element 204a and the second light-receiving element 204b will be explained. Figure 31 is a schematic diagram showing the positional relationship between the light-emitting element 202, the upper surface of the light-reflecting part 207, the first light-receiving element 204a, and the second light-receiving element 204b.

[0306] In Figure 31, position 401 indicates the reference position of the upper surface of the light-reflecting portion 207 in the z-axis direction. In this embodiment, the reference position is the position of the upper surface of the aforementioned region 207a of the light-reflecting portion 207 when the diaphragm 206 is flat. Position 402 indicates the position where the upper surface of the light-reflecting portion 207 is displaced upward by a certain displacement amount d2 from position 401. Since the displacement amount d2 of the light-reflecting portion 207 is small compared to the diameter of the diaphragm 206, even when the upper surface of the light-reflecting portion 207 is at position 402, the region 207a of the upper surface of the light-reflecting portion 207 is assumed to be flat. Furthermore, in the following description, the displacement amount d2 is assumed to be a non-negative value regardless of whether the direction of displacement is in the positive or negative direction of the z-axis.

[0307] In Figure 31, the first incident optical axis 403a indicates the optical axis of the first incident light 211a. The angle of incidence of the first incident light 211a with respect to the light reflecting part 207 is denoted as the first incident angle, and is represented by θa. The first incident angle θa is defined by the angle between the first incident optical axis 403a and the normal to the upper surface of the light reflecting part 207. The optical axis of the first reflected light 212a when the upper surface of the light reflecting part 207 is at position 401 is defined as the first reflected optical axis 404a. The optical axis of the first reflected light 212a when the upper surface of the light reflecting part 207 is at position 402 is defined as the second reflected optical axis 405a. Since the first incident light 211a is specularly reflected at the upper surface of the light reflecting part 207, the reflection angle (first reflection angle) of the first reflected light 212a is also θa. The first reflected optical axis 404a and the second reflected optical axis 405a are parallel to each other. Furthermore, when the angle of incidence of the first reflected light 212a to the first light-receiving element 204a is φa, in this embodiment φa is 0°, but φa may be other than 0°.

[0308] According to this embodiment, by configuring the system so that light emitted from one light-emitting unit is guided to multiple light-receiving units via multiple paths with different incident angles (θa, θb) relative to the light-reflecting unit 207, appropriate displacement ratios Ga and Gb can be set for multiple types of biological sounds. Therefore, multiple types of vibrations can be accurately detected with a single chestpiece 110 (detection device). Furthermore, multiple types of biological sounds can be accurately detected with a single electronic stethoscope 100. 《Sixth Embodiment》

[0309] Next, the chestpiece 1110 of the electronic stethoscope 100 according to the sixth embodiment will be described. In the following description, elements with reference numerals common to the fifth embodiment will have basically the same configuration and function as those described in the fifth embodiment unless otherwise specified, and the differences from the fifth embodiment will be mainly described.

[0310] First, the configuration of the chestpiece 1110 will be explained using Figures 32(a) and 32(b), and Figures 33(a) and 33(b). Figure 32(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line C-C in Figure 32(b). Figure 32(b) is a plan view (viewed in the negative z-axis direction) showing the internal layout of the chestpiece 1110. Figure 33(a) is a cross-sectional view of the chestpiece 1110 in the section shown by line D-D in Figure 33(b). Figure 33(b) is a plan view showing the internal layout of the chestpiece 1110. Note that in Figures 32(b) and 33(b), the components other than the housing 208 of the chestpiece 1110 are shown by viewing the housing 208 through the housing 208.

[0311] As shown in Figures 32(a) to 33(b), the chestpiece 1110 includes a holding member 1201, a light-emitting circuit board 203 including a light-emitting element 202, and light-receiving circuit boards (205a, 205b) including light-receiving elements (204a, 204b). The chestpiece 1110 also includes a diaphragm 206 including a light-reflecting portion 207 and a housing 208.

[0312] The chestpiece 1110 according to this embodiment has a plurality of light-emitting units and a plurality of light-receiving units. More specifically, the chestpiece 110 according to this embodiment has two sets of optical displacement detection mechanisms, each consisting of one light-emitting unit and one light-receiving unit. In other words, the chestpiece 1110 has a light-emitting circuit board 203 as a light-emitting unit, a first light-receiving circuit board 205a as a first light-receiving unit, and a second light-receiving circuit board 205b as a second light-receiving unit.

[0313] The housing 208 houses the holding member 1201, the light-emitting circuit board 203, and the light-receiving circuit boards (205a, 205b) inside.

[0314] As can be seen from Figures 32(b) and 33(b), when viewed in the z-axis direction, the optical path from the light-emitting element 202 to the first light-receiving element 204a and the optical path from the light-emitting element 202 to the second light-receiving element 204b do not overlap except in the vicinity of the light-emitting element 202. In particular, the optical path from the light-reflecting portion 207 to the first light-receiving element 204a and the optical path from the light-reflecting portion 207 to the second light-receiving element 204b do not overlap when viewed in the z-axis direction. Also, when viewed in the z-axis direction, the first light-receiving circuit board 205a and the second light-receiving circuit board 205b do not overlap. The first light-receiving circuit board 205a and the second light-receiving circuit board 205b are positioned apart from each other in the rotational direction around an axis that passes through the center 206e of the diaphragm 206 and extends in a direction perpendicular to the contact surface 206a of the diaphragm 206. This configuration makes it possible to avoid a decrease in detection accuracy due to light interference. In other words, when detecting vibrations of the biological surface 320 using either the first light-receiving element 204a or the second light-receiving element 204b, the influence of stray light passing through the optical path corresponding to the other light-receiving element can be reduced.

[0315] In this embodiment, the angle of incidence of light reaching the first light-receiving element 204a with respect to the light-reflecting portion 207 and the angle of incidence of light reaching the second light-receiving element 204b with respect to the light-reflecting portion 207 may be the same. In this embodiment, instead of creating a difference in the angle of incidence, a difference in the width of the aperture of the diaphragm is created, as will be explained below, to create a difference in detection range and sensitivity between the first light-receiving circuit board 205a and the second light-receiving circuit board 205b. This configuration is advantageous for miniaturizing the chestpiece 1110 in the z-axis direction compared to the configuration of the fifth embodiment in which the angle of incidence is different (Figure 29(a)).

[0316] In the examples shown in Figures 32(a)(b) and 33(a)(b), the portion of the holding member 1201 through which the first incident light 211a passes corresponds to the first aperture portion 1209a (opening). The portion of the holding member 1201 through which the second incident light 211b passes corresponds to the second aperture portion 1209b (opening).

[0317] The chestpiece 1110 has a third aperture 1210a and a fourth aperture 1210b that narrow the light specularly reflected by the light reflecting section 207. The third aperture 1210a suppresses diffusely reflected light from entering the first light-receiving element 204a, allowing only specularly reflected light from the light reflecting section 207 to reach the first light-receiving element 204a. The fourth aperture 1210b suppresses diffusely reflected light from entering the second light-receiving element 204b, allowing only specularly reflected light from the light reflecting section 207 to reach the second light-receiving element 204b. Furthermore, the third aperture 1210a and the fourth aperture 1210b further narrow the specularly reflected light from the light reflecting section 207, allowing only a portion of the specularly reflected light to reach the first light-receiving element 204a and the second light-receiving element 204b.

[0318] In the examples of Figures 32(a)(b) and 33(a)(b), the portion of the holding member 1201 through which the first reflected light 212a passes corresponds to the third diaphragm portion 1210a (first opening). Also, the portion of the holding member 201 through which the second reflected light 212b passes corresponds to the fourth diaphragm portion 1210b (second opening).

[0319] A housing 208 is attached to the outer periphery of the holding member 1201. The housing 208 covers the light-emitting circuit board 203 and the first light-receiving circuit board 205a and the second light-receiving circuit board 205b, and also suppresses ambient noise from entering the housing 208.

[0320] As shown in Figures 32(a) and 33(a), in this embodiment, the opening of the third diaphragm 1210a (third opening) is set to be narrower than the opening of the fourth diaphragm 1210b (fourth opening). In other words, the opening area of ​​the third diaphragm 1210a when viewed in the direction of the optical axis of the first reflected light 212a when the diaphragm 206 is flat is smaller than the opening area of ​​the fourth diaphragm 1210b when viewed in the direction of the optical axis of the second reflected light 212b when the diaphragm 206 is flat. Therefore, when the diaphragm 206 is flat, the area over which the first light-receiving element 204a receives the first reflected light 212a is smaller than the area over which the second light-receiving element 204b receives the second reflected light 212b from the light-reflecting part 207. [Example of operation of the electronic stethoscope according to the sixth embodiment]

[0321] Referring to Figures 34(a) and 34(b), and Figures 35(a) and 35(b), a basic example of operation of the chestpiece 1110 according to the sixth embodiment will be described. Figures 34(a) and 34(b) show an example of operation relating to the light-emitting circuit board 203 and the first light-receiving circuit board 205a. Figures 35(a) and 35(b) show an example of operation relating to the light-emitting circuit board 203 and the second light-receiving circuit board 205b.

[0322] Figure 34(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The first aperture portion 1209a and the third aperture portion 1210a are arranged so that when the diaphragm 206 is flat, more of the first reflected light 212a is received by the first light-receiving element 204a compared to when the diaphragm 206 is displaced (deformed).

[0323] The first light-receiving element 204a amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the first light-receiving circuit board 205a generates an output value as a displacement signal by converting the photocurrent output from the first light-receiving element 204a into a voltage.

[0324] Figure 34(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the light-emitting element 202 to the upper surface of the light-reflecting portion 207 decreases. As the biological surface 320 is displaced, the region 207a of the light-reflecting portion 207 to which the first incident light 211a reaches is also displaced. Furthermore, as the region 207a of the light-reflecting portion 207 is displaced, the path through which the first reflected light 212a passes also shifts upward, resulting in at least a portion of the first reflected light 212a falling outside the aperture range of the third aperture portion 1210a. As a result, the amount of light from the first reflected light 212a reaching the first photodetector 204a decreases, and the value of the displacement signal generated by the first photodetector circuit board 205a changes. In this embodiment, when the amount of light incident on the first light-receiving element 204a per unit time decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower).

[0325] Figure 35(a) shows a cross-sectional view of the chestpiece 1110 when the diaphragm 206 is flat. The second aperture portion 1209b and the fourth aperture portion 1210b are arranged so that, when the diaphragm 206 is flat, more second reflected light 212b is received by the second light-receiving element 204b compared to when the diaphragm 206 is displaced (deformed).

[0326] The second photodetector 204b amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the second photodetector circuit board 205b generates an output value as a displacement signal by converting the photocurrent output from the second photodetector 204b into a voltage.

[0327] Figure 35(b) shows a cross-sectional view of the chestpiece 1110 when the biological surface 320 is displaced upward (in the positive z-axis direction). When the biological surface 320 is displaced upward, the distance from the light-emitting element 202 to the upper surface of the light-reflecting portion 207 decreases. As the biological surface 320 is displaced, the region 207b of the light-reflecting portion 207 to which the second incident light 211b reaches is also displaced. Furthermore, as the region 207b of the light-reflecting portion 207 is displaced, the path through which the second reflected light 212b passes also shifts upward, resulting in at least a portion of the second incident light 211b falling outside the aperture range of the fourth aperture portion 1210b. As a result, the amount of light from the second reflected light 212b that reaches the second photodetector 204b decreases, and the value of the displacement signal generated by the second photodetector circuit board 205b changes. In this embodiment, when the amount of light incident on the second photodetector 204b per unit time decreases, the value of the displacement signal becomes smaller (the voltage value becomes lower).

[0328] Here, we will explain the effect of setting the opening of the third aperture 1210a to be narrower than the opening of the fourth aperture 1210b, as mentioned above. As can be seen by comparing Figure 34(a) and Figure 35(a), the opening of the fourth aperture 1210b is wider, so it can be said that the fourth aperture 1210b does not restrict the second reflected light 212b as much. Therefore, in the state where there is no displacement of the diaphragm 206 (Figure 35(a)), the amount of light incident on the second photodetector 204b is greater than the amount of light incident on the first photodetector 204a.

[0329] Furthermore, because the opening of the fourth aperture portion 1210b is wider than the opening of the third aperture portion 1210a, the change in the displacement signal emitted by the second light-receiving circuit board 205b when the diaphragm 206 is displaced is smaller than the change in the displacement signal emitted by the first light-receiving circuit board 205a. In other words, for example, as shown in Figure 34(b), if the first reflected light 212a does not reach the first light-receiving element 204a at all, the value of the displacement signal emitted by the first light-receiving circuit board 205a is ideally zero. On the other hand, as shown in Figure 35(b), if the amount of second reflected light 212b reaching the second light-receiving element 204b is halved, with the diaphragm 206 in a flat state as the reference, the value of the displacement signal emitted by the second light-receiving circuit board 205b is ideally about half.

[0330] Thus, in this embodiment, although the amount of light reaching the first light-receiving element 204a and the second light-receiving element 204b is arranged to change in accordance with the displacement of the biological surface 320, the rate of change of the displacement signal with respect to the amount of displacement of the biological surface 320 is different. [Relationship between the amount of displacement of the biological surface and the displacement signal according to the sixth embodiment]

[0331] Referring to Figure 34, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal represents the voltage output from the first light-receiving circuit board 205a and the second light-receiving circuit board 205b. The horizontal axis of Figure 34 represents the displacement d2 of the upper surface of the light-reflecting part 207 that is linked to the biological surface 320, and the vertical axis of Figure 34 represents the magnitude of the displacement signal generated by the first light-receiving circuit board 205a or the second light-receiving circuit board 205b. Graph 1500a plots the value of the displacement signal generated by the first light-receiving circuit board 205a (Sda below) for each value of displacement d2. Graph 1500b plots the value of the displacement signal generated by the second light-receiving circuit board 205b (Sdb below) for each value of displacement d2.

[0332] In this embodiment, Vmaxa is smaller than Vmaxb. Therefore, dmaxa is smaller than dmaxb. In other words, the minimum displacement d2 at which the amount of light received by the first light-receiving element 204a becomes zero is smaller than the minimum displacement d2 at which the amount of light received by the second light-receiving element 204b becomes zero. To put it another way, using the state in which the outer surface of the diaphragm 206 is not in contact with the living body as a reference, the minimum displacement of the light-reflecting part 207 at which the first reflected light 212a no longer reaches the first light-receiving element 204a (dmaxa) is smaller than the minimum displacement of the light-reflecting part 207 at which the second reflected light 212b no longer reaches the second light-receiving element 204b (dmaxb). Therefore, the detection range of the second optical detection pair, consisting of the light-emitting circuit board 203 and the second light-receiving circuit board 205b, is wider than the detection range of the first optical detection pair, consisting of the light-emitting circuit board 203 and the first light-receiving circuit board 205a.

[0333] According to the present invention, a detection device and an electronic stethoscope capable of accurately detecting multiple types of vibrations are provided.

[0334] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0335] This application claims priority based on Japanese Patent Application No. 2024-191356, Japanese Patent Application No. 2024-191357, and Japanese Patent Application No. 2024-191358, all of which were filed on October 31, 2024, and all of their contents are incorporated herein by reference.

Claims

A detection device for detecting vibrations of a subject, A diaphragm including a reflective surface that moves in response to the vibration of the subject, A first light-emitting unit that emits first light toward the reflective surface, A first light receiving unit receives the first light reflected by the reflective surface and outputs a signal corresponding to the first light, A second light-emitting unit that emits a second light toward the reflective surface, A second light receiving unit receives the second light reflected by the reflective surface and outputs a signal corresponding to the second light, Equipped with, A detection device wherein the angle of incidence of the first light to the reflective surface is greater than the angle of incidence of the second light to the reflective surface. 　 The optical axis of the first light emitted from the first light-emitting unit onto the reflective surface is defined as the first incident optical axis, the path through which the light rays incident on the reflective surface along the first incident optical axis and are specularly reflected by the reflective surface pass is defined as the first reflected optical axis, and the ratio of the displacement of the point where the first reflected optical axis intersects the light-receiving surface of the first light-receiving unit to the displacement of the reflective surface is defined as the first displacement ratio. When the optical axis of the second light emitted from the second light-emitting unit onto the reflective surface is defined as the second incident optical axis, the path taken by the light rays incident on the reflective surface along the second incident optical axis and specularly reflected by the reflective surface is defined as the second reflected optical axis, and the ratio of the displacement of the point where the second reflected optical axis intersects the light-receiving surface of the second light-receiving unit to the displacement of the reflective surface is defined as the second displacement ratio, The detection device according to claim 1, wherein the first displacement ratio is greater than the second displacement ratio. 　 The detection device according to claim 2, wherein the angle of incidence of the first light to the light-receiving surface of the first light-receiving unit is greater than or equal to the angle of incidence of the second light to the light-receiving surface of the second light-receiving unit. 　 A first aperture is provided that narrows the optical path from the reflective surface toward the first light-receiving unit such that the area of ​​the portion of the light-receiving surface of the first light-receiving unit that receives the first light changes according to the amount of displacement of the reflective surface, A second aperture is provided that narrows the optical path from the reflective surface toward the second light-receiving unit, such that the area of ​​the portion of the light-receiving surface of the second light-receiving unit that receives the second light changes according to the amount of displacement of the reflective surface, The detection device according to claim 1, further comprising the following: 　 A detection device for detecting vibrations of a subject, A diaphragm including a reflective surface that moves in response to the vibration of the subject, A first light-emitting unit that emits first light toward the reflective surface, A first light receiving unit receives the first light reflected by the reflective surface and outputs a signal corresponding to the first light, A second light-emitting unit that emits a second light toward the reflective surface, A second light receiving unit receives the second light reflected by the reflective surface and outputs a signal corresponding to the second light, A first aperture that narrows the optical path of the first light so that the amount of the first light reaching the first light receiving unit changes according to the amount of displacement of the reflective surface, A second aperture that narrows the optical path of the second light so that the amount of the second light reaching the second light receiving unit changes according to the amount of displacement of the reflective surface, Equipped with, A detection device in which the opening area of ​​the first opening is smaller than the opening area of ​​the second opening. 　 The detection device according to claim 5, wherein, with reference to a state in which the outer surface of the diaphragm is not in contact with the object to be tested, the minimum displacement of the reflective surface at which the first light no longer reaches the first light receiving unit is smaller than the minimum displacement of the reflective surface at which the second light no longer reaches the second light receiving unit. 　 The detection device according to claim 6, wherein, when the amount of displacement of the reflective surface is less than or equal to the minimum amount of displacement of the reflective surface at which the first light no longer reaches the first light receiving unit, the rate of change of the amount of the first light reaching the first light receiving unit with respect to the amount of displacement of the reflective surface is greater than the rate of change of the amount of the second light reaching the second light receiving unit with respect to the amount of displacement of the reflective surface. 　 The detection device according to claim 5, wherein the amount of light emitted by the first light-emitting unit is greater than the amount of light emitted by the second light-emitting unit. 　 The detection device according to claim 1, wherein, when viewed in the direction normal to the outer surface at the center of the outer surface of the diaphragm, the optical path of the first light from the first light-emitting unit toward the first light-receiving unit via the reflective surface and the optical path of the second light from the second light-emitting unit toward the second light-receiving unit via the reflective surface intersect. 　 Of the reflective surfaces, the range that reflects the first light reaching the first light receiving unit when the diaphragm is not pressed against the object is defined as the first effective range. When the range of the reflective surface that reflects the second light reaching the second light receiving unit when the diaphragm is not pressed against the subject is defined as the second effective range, The detection device according to claim 9, wherein, when viewed in the normal direction, the first effective range and the second effective range each overlap with the center of the diaphragm. 　 The detection device according to claim 1, configured to switch between a first mode in which vibrations in a first frequency band are detected using the first light-emitting unit and the first light-receiving unit, and a second mode in which vibrations in a second frequency band lower than the first frequency band are detected using the second light-emitting unit and the second light-receiving unit. 　 The first mode is a mode for detecting breath sounds, The detection device according to claim 11, wherein the second mode is a mode for detecting heart sounds. 　 A detection device according to any one of claims 1 to 12, An electronic stethoscope comprising: a sound output unit that outputs a signal to a sound output device to emit sound based on a signal generated by the detection device.

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